pgsql: Don't allow CREATE TABLE AS to put relations in pg_global.

Don't allow CREATE TABLE AS to put relations in pg_global.

This was never intended to be allowed, and is blocked for an ordinary
CREATE TABLE, but CREATE TABLE AS slipped through the cracks.  This
commit won't do anything to fix existing cases where this has loophole
has been exploited, but it still seems prudent to lock it down going
forward.

Back-branch commit only, as this problem has been refactored away
on the master branch.

Andres Freund

Branch
------
REL8_3_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/596e16320e9638d46ae640b6fddde6cf9cadb93c

Modified Files
--------------
src/backend/executor/execMain.c |    7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)