pgsql: Unbreak unlogged tables.

Unbreak unlogged tables.

I broke this in commit 5da79169d3e9f0fab47da03318c44075b3f824c5, which
was obviously insufficiently well tested.  Add some regression tests
in the hope of making future slip-ups more likely to be noticed.

Branch
------
REL9_1_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/16a6a70ea37be76b7c3757503defbbd05d2acdf1

Modified Files
--------------
src/backend/catalog/namespace.c            |    7 ++++---
src/test/regress/expected/create_table.out |   11 +++++++++++
src/test/regress/sql/create_table.sql      |   10 ++++++++++
3 files changed, 25 insertions(+), 3 deletions(-)