pgsql: Code review for array_fill patch: fix inadequate check for array

Log Message:
-----------
Code review for array_fill patch: fix inadequate check for array size overflow
and bogus documentation (dimension arrays are int[] not anyarray). Also the
errhint() messages seem to be really errdetail(), since there is nothing
heuristic about them. Some other trivial cosmetic improvements.

Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.442 -> r1.443)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.442&r2=1.443)
pgsql/src/backend/utils/adt:
arrayfuncs.c (r1.146 -> r1.147)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/arrayfuncs.c?r1=1.146&r2=1.147)
pgsql/src/test/regress/expected:
arrays.out (r1.37 -> r1.38)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/arrays.out?r1=1.37&r2=1.38)