Mark built-in coercion functions as leakproof where possible.

Making these leakproof seems helpful since (for example) if you have a
function f(int8) that is leakproof, you don't want it to effectively
become non-leakproof when you apply it to an int4 or int2 column.
But that's what happens today, since the implicit up-coercion will
not be leakproof.

Most of the coercion functions that visibly can't throw errors are
functions that convert numeric datatypes to other, wider ones.
Notable is that float4_numeric and float8_numeric can be marked
leakproof; before commit a57d312a they could not have been.
I also marked the functions that coerce strings to "name" as leakproof;
that's okay today because they truncate silently, but if we ever
reconsidered that behavior then they could no longer be leakproof.

I desisted from marking rtrim1() as leakproof; it appears so right now,
but the code seems a little too complex and perhaps subject to change,
since it's shared with other SQL functions.

Discussion: https://postgr.es/m/459322.1595607431@sss.pgh.pa.us

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202007202
+#define CATALOG_VERSION_NO	202007251
 
 #endif

src/test/regress/expected/opr_sanity.out

@@ -572,6 +572,8 @@ int24ge(smallint,integer)
 int42ge(integer,smallint)
 oideq(oid,oid)
 oidne(oid,oid)
+float8(smallint)
+float4(smallint)
 nameeqtext(name,text)
 namelttext(name,text)
 nameletext(name,text)
@@ -610,6 +612,10 @@ float84lt(double precision,real)
 float84le(double precision,real)
 float84gt(double precision,real)
 float84ge(double precision,real)
+float8(real)
+int4(smallint)
+float8(integer)
+float4(integer)
 btint2cmp(smallint,smallint)
 btint4cmp(integer,integer)
 btfloat4cmp(real,real)
@@ -620,6 +626,9 @@ btnamecmp(name,name)
 bttextcmp(text,text)
 cash_cmp(money,money)
 btoidvectorcmp(oidvector,oidvector)
+text(name)
+name(text)
+name(character)
 text_larger(text,text)
 text_smaller(text,text)
 int8eq(bigint,bigint)
@@ -634,7 +643,10 @@ int84lt(bigint,integer)
 int84gt(bigint,integer)
 int84le(bigint,integer)
 int84ge(bigint,integer)
+int8(integer)
+float8(bigint)
 oidvectorne(oidvector,oidvector)
+float4(bigint)
 namelt(name,name)
 namele(name,name)
 namegt(name,name)
@@ -651,6 +663,7 @@ text_lt(text,text)
 text_le(text,text)
 text_gt(text,text)
 text_ge(text,text)
+int8(smallint)
 macaddr_eq(macaddr,macaddr)
 macaddr_lt(macaddr,macaddr)
 macaddr_le(macaddr,macaddr)
@@ -716,6 +729,7 @@ interval_ge(interval,interval)
 interval_gt(interval,interval)
 charlt("char","char")
 tidne(tid,tid)
+int8(oid)
 tideq(tid,tid)
 timestamptz_cmp(timestamp with time zone,timestamp with time zone)
 interval_cmp(interval,interval)
@@ -727,6 +741,9 @@ timetz_le(time with time zone,time with time zone)
 timetz_ge(time with time zone,time with time zone)
 timetz_gt(time with time zone,time with time zone)
 timetz_cmp(time with time zone,time with time zone)
+"interval"(time without time zone)
+name(character varying)
+"varchar"(name)
 circle_eq(circle,circle)
 circle_ne(circle,circle)
 circle_lt(circle,circle)
@@ -757,6 +774,11 @@ varbitcmp(bit varying,bit varying)
 boolle(boolean,boolean)
 boolge(boolean,boolean)
 btboolcmp(boolean,boolean)
+"numeric"(integer)
+"numeric"(real)
+"numeric"(double precision)
+"numeric"(bigint)
+"numeric"(smallint)
 int28eq(smallint,bigint)
 int28ne(smallint,bigint)
 int28lt(smallint,bigint)
@@ -803,6 +825,8 @@ btfloat48cmp(real,double precision)
 btfloat84cmp(double precision,real)
 md5(text)
 md5(bytea)
+bool(integer)
+int4(boolean)
 tidgt(tid,tid)
 tidlt(tid,tid)
 tidge(tid,tid)
@@ -837,6 +861,7 @@ macaddr8_gt(macaddr8,macaddr8)
 macaddr8_ge(macaddr8,macaddr8)
 macaddr8_ne(macaddr8,macaddr8)
 macaddr8_cmp(macaddr8,macaddr8)
+macaddr8(macaddr)
 xid8lt(xid8,xid8)
 xid8gt(xid8,xid8)
 xid8le(xid8,xid8)