pgsql: Finish disabling reduced-lock-levels-for-DDL feature.

Finish disabling reduced-lock-levels-for-DDL feature.

Previous patch only covered the ALTER TABLE changes, not changes in other
commands; and it neglected to revert the documentation changes.

Branch
------
REL9_1_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/ec1339ea5cb591da53ad7584ffc29e120f6bf74f

Modified Files
--------------
doc/src/sgml/mvcc.sgml | 9 ++++-----
src/backend/commands/tablecmds.c | 17 +++++++++++------
src/backend/commands/trigger.c | 18 ++++--------------
src/backend/rewrite/rewriteDefine.c | 12 +++++-------
4 files changed, 24 insertions(+), 32 deletions(-)