pgsql: Support CREATE SCHEMA IF NOT EXISTS.

Support CREATE SCHEMA IF NOT EXISTS.

Per discussion, schema-element subcommands are not allowed together with
this option, since it's not very obvious what should happen to the element
objects.

Fabrízio de Royes Mello

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/fb34e94d214d6767910df47aa7c605c452d11c57

Modified Files
--------------
doc/src/sgml/ref/create_schema.sgml     |   27 +++++++++++++++++++++++
src/backend/commands/extension.c        |    1 +
src/backend/commands/schemacmds.c       |   17 +++++++++++++++
src/backend/nodes/copyfuncs.c           |    1 +
src/backend/nodes/equalfuncs.c          |    1 +
src/backend/parser/gram.y               |   35 +++++++++++++++++++++++++++++++
src/include/nodes/parsenodes.h          |    1 +
src/test/regress/expected/namespace.out |   13 +++++++++++
src/test/regress/sql/namespace.sql      |    9 ++++++++
9 files changed, 105 insertions(+), 0 deletions(-)