pgsql: Add a couple of information functions to support direct checks on

Log Message:
-----------
Add a couple of information functions to support direct checks on whether
a schema is our own temp schema or another backend's temp schema, and use
these in place of some former kluges in information_schema. Per my
proposal of yesterday.

Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.336 -> r1.337)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.336&r2=1.337)
pgsql/src/backend/catalog:
information_schema.sql (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/information_schema.sql.diff?r1=1.36&r2=1.37)
namespace.c (r1.86 -> r1.87)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/namespace.c.diff?r1=1.86&r2=1.87)
pgsql/src/include/catalog:
catversion.h (r1.355 -> r1.356)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.355&r2=1.356)
pg_proc.h (r1.423 -> r1.424)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.423&r2=1.424)