Replace raw timezone source data with IANA's new compact format.

Traditionally IANA has distributed their timezone data in pure source
form, replete with extensive historical comments.  As of release 2017c,
they've added a compact single-file format that omits comments and
abbreviates command keywords.  This form is way shorter than the pure
source, even before considering its allegedly better compressibility.
Hence, let's distribute the data in that form rather than pure source.

I'm pushing this now, rather than at the next timezone database update,
so that it's easy to confirm that this data file produces compiled zic
output that's identical to what we were getting before.

Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us

src/timezone/Makefile

@@ -21,10 +21,8 @@ OBJS= localtime.o strftime.o pgtz.o
 # files needed to build zic utility program
 ZICOBJS= zic.o $(WIN32RES)
 
-# timezone data files
-TZDATA = africa antarctica asia australasia europe northamerica southamerica \
-	pacificnew etcetera factory backward systemv
-TZDATAFILES = $(TZDATA:%=$(srcdir)/data/%)
+# we now distribute the timezone data as a single file
+TZDATAFILES = $(srcdir)/data/tzdata.zi
 
 # which zone should determine the DST rules (not the specific UTC offset!)
 # for POSIX-style timezone specs

src/timezone/README

@@ -2,10 +2,12 @@ src/timezone/README
 
 This is a PostgreSQL adapted version of the IANA timezone library from
 
-	http://www.iana.org/time-zones
+	https://www.iana.org/time-zones
 
-The latest versions of both the tzdata and tzcode tarballs are normally
-available right from that page.  Historical versions can be found
+The latest version of the timezone data and library source code is
+available right from that page.  It's best to get the merged file
+tzdb-NNNNX.tar.lz, since the other archive formats omit tzdata.zi.
+Historical versions, as well as release announcements, can be found
 elsewhere on the site.
 
 Since time zone rules change frequently in some parts of the world,
@@ -17,11 +19,14 @@ changes that might affect interpretation of the data files.
 Time Zone data
 ==============
 
-The data files under data/ are an exact copy of the latest tzdata set,
-except that we omit some files that are not of interest for our purposes.
+We distribute the time zone source data as-is under src/timezone/data/.
+Currently, we distribute just the abbreviated single-file format
+"tzdata.zi", to reduce the size of our tarballs as well as churn
+in our git repo.  Feeding that file to zic produces the same compiled
+output as feeding the bulkier individual data files would do.
 
-While the files under data/ can just be duplicated when updating, manual
-effort is needed to update the time zone abbreviation lists under tznames/.
+While data/tzdata.zi can just be duplicated when updating, manual effort
+is needed to update the time zone abbreviation lists under tznames/.
 These need to be changed whenever new abbreviations are invented or the
 UTC offset associated with an existing abbreviation changes.  To detect
 if this has happened, after installing new files under data/ do

src/timezone/data/backward

-# This file is in the public domain, so clarified as of
-# 2009-05-17 by Arthur David Olson.
-
-# This file provides links between current names for time zones
-# and their old names.  Many names changed in late 1993.
-
-# Link	TARGET			LINK-NAME
-Link	Africa/Nairobi		Africa/Asmera
-Link	Africa/Abidjan		Africa/Timbuktu
-Link	America/Argentina/Catamarca	America/Argentina/ComodRivadavia
-Link	America/Adak		America/Atka
-Link	America/Argentina/Buenos_Aires	America/Buenos_Aires
-Link	America/Argentina/Catamarca	America/Catamarca
-Link	America/Atikokan	America/Coral_Harbour
-Link	America/Argentina/Cordoba	America/Cordoba
-Link	America/Tijuana		America/Ensenada
-Link	America/Indiana/Indianapolis	America/Fort_Wayne
-Link	America/Indiana/Indianapolis	America/Indianapolis
-Link	America/Argentina/Jujuy	America/Jujuy
-Link	America/Indiana/Knox	America/Knox_IN
-Link	America/Kentucky/Louisville	America/Louisville
-Link	America/Argentina/Mendoza	America/Mendoza
-Link	America/Toronto		America/Montreal
-Link	America/Rio_Branco	America/Porto_Acre
-Link	America/Argentina/Cordoba	America/Rosario
-Link	America/Tijuana		America/Santa_Isabel
-Link	America/Denver		America/Shiprock
-Link	America/Port_of_Spain	America/Virgin
-Link	Pacific/Auckland	Antarctica/South_Pole
-Link	Asia/Ashgabat		Asia/Ashkhabad
-Link	Asia/Kolkata		Asia/Calcutta
-Link	Asia/Shanghai		Asia/Chongqing
-Link	Asia/Shanghai		Asia/Chungking
-Link	Asia/Dhaka		Asia/Dacca
-Link	Asia/Shanghai		Asia/Harbin
-Link	Asia/Urumqi		Asia/Kashgar
-Link	Asia/Kathmandu		Asia/Katmandu
-Link	Asia/Macau		Asia/Macao
-Link	Asia/Yangon		Asia/Rangoon
-Link	Asia/Ho_Chi_Minh	Asia/Saigon
-Link	Asia/Jerusalem		Asia/Tel_Aviv
-Link	Asia/Thimphu		Asia/Thimbu
-Link	Asia/Makassar		Asia/Ujung_Pandang
-Link	Asia/Ulaanbaatar	Asia/Ulan_Bator
-Link	Atlantic/Faroe		Atlantic/Faeroe
-Link	Europe/Oslo		Atlantic/Jan_Mayen
-Link	Australia/Sydney	Australia/ACT
-Link	Australia/Sydney	Australia/Canberra
-Link	Australia/Lord_Howe	Australia/LHI
-Link	Australia/Sydney	Australia/NSW
-Link	Australia/Darwin	Australia/North
-Link	Australia/Brisbane	Australia/Queensland
-Link	Australia/Adelaide	Australia/South
-Link	Australia/Hobart	Australia/Tasmania
-Link	Australia/Melbourne	Australia/Victoria
-Link	Australia/Perth		Australia/West
-Link	Australia/Broken_Hill	Australia/Yancowinna
-Link	America/Rio_Branco	Brazil/Acre
-Link	America/Noronha		Brazil/DeNoronha
-Link	America/Sao_Paulo	Brazil/East
-Link	America/Manaus		Brazil/West
-Link	America/Halifax		Canada/Atlantic
-Link	America/Winnipeg	Canada/Central
-# This line is commented out, as the name exceeded the 14-character limit
-# and was an unused misnomer.
-#Link	America/Regina		Canada/East-Saskatchewan
-Link	America/Toronto		Canada/Eastern
-Link	America/Edmonton	Canada/Mountain
-Link	America/St_Johns	Canada/Newfoundland
-Link	America/Vancouver	Canada/Pacific
-Link	America/Regina		Canada/Saskatchewan
-Link	America/Whitehorse	Canada/Yukon
-Link	America/Santiago	Chile/Continental
-Link	Pacific/Easter		Chile/EasterIsland
-Link	America/Havana		Cuba
-Link	Africa/Cairo		Egypt
-Link	Europe/Dublin		Eire
-Link	Europe/London		Europe/Belfast
-Link	Europe/Chisinau		Europe/Tiraspol
-Link	Europe/London		GB
-Link	Europe/London		GB-Eire
-Link	Etc/GMT			GMT+0
-Link	Etc/GMT			GMT-0
-Link	Etc/GMT			GMT0
-Link	Etc/GMT			Greenwich
-Link	Asia/Hong_Kong		Hongkong
-Link	Atlantic/Reykjavik	Iceland
-Link	Asia/Tehran		Iran
-Link	Asia/Jerusalem		Israel
-Link	America/Jamaica		Jamaica
-Link	Asia/Tokyo		Japan
-Link	Pacific/Kwajalein	Kwajalein
-Link	Africa/Tripoli		Libya
-Link	America/Tijuana		Mexico/BajaNorte
-Link	America/Mazatlan	Mexico/BajaSur
-Link	America/Mexico_City	Mexico/General
-Link	Pacific/Auckland	NZ
-Link	Pacific/Chatham		NZ-CHAT
-Link	America/Denver		Navajo
-Link	Asia/Shanghai		PRC
-Link	Pacific/Honolulu	Pacific/Johnston
-Link	Pacific/Pohnpei		Pacific/Ponape
-Link	Pacific/Pago_Pago	Pacific/Samoa
-Link	Pacific/Chuuk		Pacific/Truk
-Link	Pacific/Chuuk		Pacific/Yap
-Link	Europe/Warsaw		Poland
-Link	Europe/Lisbon		Portugal
-Link	Asia/Taipei		ROC
-Link	Asia/Seoul		ROK
-Link	Asia/Singapore		Singapore
-Link	Europe/Istanbul		Turkey
-Link	Etc/UCT			UCT
-Link	America/Anchorage	US/Alaska
-Link	America/Adak		US/Aleutian
-Link	America/Phoenix		US/Arizona
-Link	America/Chicago		US/Central
-Link	America/Indiana/Indianapolis	US/East-Indiana
-Link	America/New_York	US/Eastern
-Link	Pacific/Honolulu	US/Hawaii
-Link	America/Indiana/Knox	US/Indiana-Starke
-Link	America/Detroit		US/Michigan
-Link	America/Denver		US/Mountain
-Link	America/Los_Angeles	US/Pacific
-Link	Pacific/Pago_Pago	US/Samoa
-Link	Etc/UTC			UTC
-Link	Etc/UTC			Universal
-Link	Europe/Moscow		W-SU
-Link	Etc/UTC			Zulu

src/timezone/data/etcetera

-# This file is in the public domain, so clarified as of
-# 2009-05-17 by Arthur David Olson.
-
-# These entries are mostly present for historical reasons, so that
-# people in areas not otherwise covered by the tz files could "zic -l"
-# to a time zone that was right for their area.  These days, the
-# tz files cover almost all the inhabited world, and the only practical
-# need now for the entries that are not on UTC are for ships at sea
-# that cannot use POSIX TZ settings.
-
-# Starting with POSIX 1003.1-2001, the entries below are all
-# unnecessary as settings for the TZ environment variable.  E.g.,
-# instead of TZ='Etc/GMT+4' one can use the POSIX setting TZ='<-04>+4'.
-#
-# Do not use a POSIX TZ setting like TZ='GMT+4', which is four hours
-# behind GMT but uses the completely misleading abbreviation "GMT".
-
-Zone	Etc/GMT		0	-	GMT
-Zone	Etc/UTC		0	-	UTC
-Zone	Etc/UCT		0	-	UCT
-
-# The following link uses older naming conventions,
-# but it belongs here, not in the file 'backward',
-# as functions like gmtime load the "GMT" file to handle leap seconds properly.
-# We want this to work even on installations that omit the other older names.
-Link	Etc/GMT				GMT
-
-Link	Etc/UTC				Etc/Universal
-Link	Etc/UTC				Etc/Zulu
-
-Link	Etc/GMT				Etc/Greenwich
-Link	Etc/GMT				Etc/GMT-0
-Link	Etc/GMT				Etc/GMT+0
-Link	Etc/GMT				Etc/GMT0
-
-# Be consistent with POSIX TZ settings in the Zone names,
-# even though this is the opposite of what many people expect.
-# POSIX has positive signs west of Greenwich, but many people expect
-# positive signs east of Greenwich.  For example, TZ='Etc/GMT+4' uses
-# the abbreviation "-04" and corresponds to 4 hours behind UT
-# (i.e. west of Greenwich) even though many people would expect it to
-# mean 4 hours ahead of UT (i.e. east of Greenwich).
-
-# Earlier incarnations of this package were not POSIX-compliant,
-# and had lines such as
-#		Zone	GMT-12		-12	-	GMT-1200
-# We did not want things to change quietly if someone accustomed to the old
-# way does a
-#		zic -l GMT-12
-# so we moved the names into the Etc subdirectory.
-# Also, the time zone abbreviations are now compatible with %z.
-
-Zone	Etc/GMT-14	14	-	+14
-Zone	Etc/GMT-13	13	-	+13
-Zone	Etc/GMT-12	12	-	+12
-Zone	Etc/GMT-11	11	-	+11
-Zone	Etc/GMT-10	10	-	+10
-Zone	Etc/GMT-9	9	-	+09
-Zone	Etc/GMT-8	8	-	+08
-Zone	Etc/GMT-7	7	-	+07
-Zone	Etc/GMT-6	6	-	+06
-Zone	Etc/GMT-5	5	-	+05
-Zone	Etc/GMT-4	4	-	+04
-Zone	Etc/GMT-3	3	-	+03
-Zone	Etc/GMT-2	2	-	+02
-Zone	Etc/GMT-1	1	-	+01
-Zone	Etc/GMT+1	-1	-	-01
-Zone	Etc/GMT+2	-2	-	-02
-Zone	Etc/GMT+3	-3	-	-03
-Zone	Etc/GMT+4	-4	-	-04
-Zone	Etc/GMT+5	-5	-	-05
-Zone	Etc/GMT+6	-6	-	-06
-Zone	Etc/GMT+7	-7	-	-07
-Zone	Etc/GMT+8	-8	-	-08
-Zone	Etc/GMT+9	-9	-	-09
-Zone	Etc/GMT+10	-10	-	-10
-Zone	Etc/GMT+11	-11	-	-11
-Zone	Etc/GMT+12	-12	-	-12

src/timezone/data/factory

-# This file is in the public domain, so clarified as of
-# 2009-05-17 by Arthur David Olson.
-
-# For distributors who don't want to put time zone specification in
-# their installation procedures.  Users that run 'date' will get the
-# time zone abbreviation "-00", indicating that the actual time zone
-# is unknown.
-
-# Zone	NAME	GMTOFF	RULES	FORMAT
-Zone	Factory	0	-	-00

src/timezone/data/pacificnew

-# This file is in the public domain, so clarified as of
-# 2009-05-17 by Arthur David Olson.
-
-# From Arthur David Olson (1989-04-05):
-# On 1989-04-05, the U. S. House of Representatives passed (238-154) a bill
-# establishing "Pacific Presidential Election Time"; it was not acted on
-# by the Senate or signed into law by the President.
-# You might want to change the "PE" (Presidential Election) below to
-# "Q" (Quadrennial) to maintain three-character zone abbreviations.
-# If you're really conservative, you might want to change it to "D".
-# Avoid "L" (Leap Year), which won't be true in 2100.
-
-# If Presidential Election Time is ever established, replace "XXXX" below
-# with the year the law takes effect and uncomment the "##" lines.
-
-# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-## Rule	Twilite	XXXX	max	-	Apr	Sun>=1	2:00	1:00	D
-## Rule	Twilite	XXXX	max	uspres	Oct	lastSun	2:00	1:00	PE
-## Rule	Twilite	XXXX	max	uspres	Nov	Sun>=7	2:00	0	S
-## Rule	Twilite	XXXX	max	nonpres	Oct	lastSun	2:00	0	S
-
-# Zone	NAME			GMTOFF	RULES/SAVE	FORMAT	[UNTIL]
-## Zone	America/Los_Angeles-PET	-8:00	US		P%sT	XXXX
-##				-8:00	Twilite		P%sT
-
-# For now...
-Link	America/Los_Angeles	US/Pacific-New	##

src/timezone/data/systemv

-# This file is in the public domain, so clarified as of
-# 2009-05-17 by Arthur David Olson.
-
-# Old rules, should the need arise.
-# No attempt is made to handle Newfoundland, since it cannot be expressed
-# using the System V "TZ" scheme (half-hour offset), or anything outside
-# North America (no support for non-standard DST start/end dates), nor
-# the changes in the DST rules in the US after 1976 (which occurred after
-# the old rules were written).
-#
-# If you need the old rules, uncomment ## lines.
-# Compile this *without* leap second correction for true conformance.
-
-# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-Rule	SystemV	min	1973	-	Apr	lastSun	2:00	1:00	D
-Rule	SystemV	min	1973	-	Oct	lastSun	2:00	0	S
-Rule	SystemV	1974	only	-	Jan	6	2:00	1:00	D
-Rule	SystemV	1974	only	-	Nov	lastSun	2:00	0	S
-Rule	SystemV	1975	only	-	Feb	23	2:00	1:00	D
-Rule	SystemV	1975	only	-	Oct	lastSun	2:00	0	S
-Rule	SystemV	1976	max	-	Apr	lastSun	2:00	1:00	D
-Rule	SystemV	1976	max	-	Oct	lastSun	2:00	0	S
-
-# Zone	NAME		GMTOFF	RULES/SAVE	FORMAT	[UNTIL]
-## Zone	SystemV/AST4ADT	-4:00	SystemV		A%sT
-## Zone	SystemV/EST5EDT	-5:00	SystemV		E%sT
-## Zone	SystemV/CST6CDT	-6:00	SystemV		C%sT
-## Zone	SystemV/MST7MDT	-7:00	SystemV		M%sT
-## Zone	SystemV/PST8PDT	-8:00	SystemV		P%sT
-## Zone	SystemV/YST9YDT	-9:00	SystemV		Y%sT
-## Zone	SystemV/AST4	-4:00	-		AST
-## Zone	SystemV/EST5	-5:00	-		EST
-## Zone	SystemV/CST6	-6:00	-		CST
-## Zone	SystemV/MST7	-7:00	-		MST
-## Zone	SystemV/PST8	-8:00	-		PST
-## Zone	SystemV/YST9	-9:00	-		YST
-## Zone	SystemV/HST10	-10:00	-		HST