pgsql: Issue error on SET outside transaction block in some cases

Issue error on SET outside transaction block in some cases

Issue error for SET LOCAL/CONSTRAINTS/TRANSACTION outside a transaction
block, as they have no effect.

Per suggestion from Morten Hustveit

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/a54141aebcafa02cba5204596758dadbbeb0f78e

Modified Files
--------------
doc/src/sgml/ref/set.sgml             |    7 +++----
doc/src/sgml/ref/set_constraints.sgml |    2 +-
doc/src/sgml/ref/set_transaction.sgml |    5 ++---
src/backend/tcop/utility.c            |    3 ++-
src/backend/utils/misc/guc.c          |   15 +++++++++++++--
src/include/utils/guc.h               |    2 +-
src/test/regress/expected/guc.out     |    2 ++
7 files changed, 24 insertions(+), 12 deletions(-)