pgsql: Adjust many backend functions to return OID rather than void.

Adjust many backend functions to return OID rather than void.

Extracted from a larger patch by Dimitri Fontaine. It is hoped that
this will provide infrastructure for enriching the new event trigger
functionality, but it seems possibly useful for other purposes as
well.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/c504513f83a9ee8dce4a719746ca73102cae9f13

Modified Files
--------------
src/backend/catalog/pg_aggregate.c | 4 +-
src/backend/catalog/pg_operator.c | 4 +-
src/backend/commands/aggregatecmds.c | 24 ++++---
src/backend/commands/alter.c | 127 +++++++++++++-------------------
src/backend/commands/collationcmds.c | 12 +++-
src/backend/commands/conversioncmds.c | 10 ++-
src/backend/commands/dbcommands.c | 10 ++-
src/backend/commands/event_trigger.c | 14 +++-
src/backend/commands/extension.c | 12 ++-
src/backend/commands/foreigncmds.c | 28 ++++++-
src/backend/commands/functioncmds.c | 58 ++++++++-------
src/backend/commands/opclasscmds.c | 8 ++-
src/backend/commands/operatorcmds.c | 26 ++++----
src/backend/commands/proclang.c | 7 ++-
src/backend/commands/schemacmds.c | 20 ++++-
src/backend/commands/sequence.c | 10 ++-
src/backend/commands/tablecmds.c | 41 +++++++----
src/backend/commands/tablespace.c | 6 ++-
src/backend/commands/trigger.c | 6 ++-
src/backend/commands/tsearchcmds.c | 38 +++++++---
src/backend/commands/typecmds.c | 84 ++++++++++++----------
src/backend/commands/user.c | 4 +-
src/backend/commands/view.c | 4 +-
src/include/catalog/pg_operator.h | 2 +-
src/include/commands/alter.h | 6 +-
src/include/commands/collationcmds.h | 6 +-
src/include/commands/conversioncmds.h | 4 +-
src/include/commands/dbcommands.h | 4 +-
src/include/commands/defrem.h | 42 ++++++------
src/include/commands/extension.h | 4 +-
src/include/commands/proclang.h | 2 +-
src/include/commands/schemacmds.h | 6 +-
src/include/commands/sequence.h | 4 +-
src/include/commands/tablecmds.h | 6 +-
src/include/commands/tablespace.h | 2 +-
src/include/commands/trigger.h | 2 +-
src/include/commands/typecmds.h | 10 ++--
src/include/commands/user.h | 2 +-
src/include/commands/view.h | 2 +-
39 files changed, 385 insertions(+), 276 deletions(-)