pgsql: Add pg_typeof() function.

Log Message:
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Add pg_typeof() function.

Brendan Jurd

Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.451 -> r1.452)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.451&r2=1.452)
pgsql/src/backend/utils/adt:
misc.c (r1.64 -> r1.65)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/misc.c?r1=1.64&r2=1.65)
pgsql/src/include/catalog:
catversion.h (r1.500 -> r1.501)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.500&r2=1.501)
pg_proc.h (r1.520 -> r1.521)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.520&r2=1.521)
pgsql/src/include/utils:
builtins.h (r1.324 -> r1.325)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h?r1=1.324&r2=1.325)
pgsql/src/test/regress/expected:
polymorphism.out (r1.13 -> r1.14)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/polymorphism.out?r1=1.13&r2=1.14)
pgsql/src/test/regress/sql:
polymorphism.sql (r1.6 -> r1.7)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/polymorphism.sql?r1=1.6&r2=1.7)