pgsql: Allow CREATE TABLE IF EXIST so succeed if the schema is nonexist

Allow CREATE TABLE IF EXIST so succeed if the schema is nonexistent

Previously, CREATE TABLE IF EXIST threw an error if the schema was
nonexistent.  This was done by passing 'missing_ok' to the function that
looks up the schema oid.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/7e2322dff30c04d90c0602d2b5ae24b4881db88b

Modified Files
--------------
src/backend/catalog/aclchk.c       |    2 +-
src/backend/catalog/namespace.c    |   86 +++++++++++++++++++++++------------
src/backend/commands/indexcmds.c   |    2 +-
src/backend/commands/opclasscmds.c |    4 +-
src/backend/commands/trigger.c     |    3 +-
src/backend/parser/parse_oper.c    |    2 +-
src/backend/parser/parse_type.c    |    2 +-
src/backend/utils/adt/xml.c        |    6 +-
src/include/catalog/namespace.h    |    2 +-
9 files changed, 68 insertions(+), 41 deletions(-)