Fix harmless LC_COLLATE[_MASK] confusion.

Commit ca051d8b10 called newlocale(LC_COLLATE, ...) instead of
newlocale(LC_COLLATE_MASK, ...), in code reached only on FreeBSD.  They
have the same value on that OS, explaining why it worked.  Fix.

Back-patch to 14, where ca051d8b10 landed.

src/backend/utils/adt/pg_locale.c

@@ -1755,7 +1755,7 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 		locale_t	loc;
 
 		/* Look up FreeBSD collation version. */
-		loc = newlocale(LC_COLLATE, collcollate, NULL);
+		loc = newlocale(LC_COLLATE_MASK, collcollate, NULL);
 		if (loc)
 		{
 			collversion =