database.

POSIX-style timezone specs that don't exactly match any database entry will
be treated as having correct USA DST rules.  Also, document that this can
be changed if you want to use some other DST rules with a POSIX zone spec.

We could consider changing localtime.c's TZDEFRULESTRING, but since that
facility can only deal with one DST transition rule, it seems fairly useless
now; might as well just plan to override it using a "posixrules" entry.

Backpatch as far as 8.0.  There isn't much we can do in 7.x ... either your
libc gets it right, or it doesn't.

configuration files that can be altered by a DBA.  The australian_timezones
GUC setting disappears, replaced by a timezone_abbreviations setting (set this
to 'Australia' to get the effect of australian_timezones).  The list of zone
names defined by default has undergone a bit of cleanup, too.  Documentation
still needs some work --- in particular, should we fix Table B-4, or just get
rid of it?  Joachim Wieland, with some editorializing by moi.

problems:

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Support cross compilation by compiling "zic" with a native compiler.
This relies on the output of zic being platform independent, but that is
currently the case.

changes.

relies on the output of zic being platform independent, but that is
currently the case.

library that uses palloc, ereport, etc.  This simplifies the makefiles
for client applications.

and should do now that we control our own destiny for timezone handling,
but this commit gets the bulk of the picayune diffs in place.
Magnus Hagander and Tom Lane.

Create new get_* functions to access compiled-in paths and adjust if
relative installs are to be used.

Clean up substitute_libpath_macro() code.

Move timezone database to share/timezone.

system headers.

Allow system to find timezone database by pasing pkglibdir into the
binary via a define.

Timezone code backend integration done by Magnus Hagander.