pgsql: Support opfamily members in get_object_address

Support opfamily members in get_object_address

In the spirit of 890192e99af and 4464303405f: have get_object_address
understand individual pg_amop and pg_amproc objects.  There is no way to
refer to such objects directly in the grammar -- rather, they are almost
always considered an integral part of the opfamily that contains them.
(The only case that deals with them individually is ALTER OPERATOR
FAMILY ADD/DROP, which carries the opfamily address separately and thus
does not need it to be part of each added/dropped element's address.)
In event triggers it becomes possible to become involved with individual
amop/amproc elements, and this commit enables pg_get_object_address to
do so as well.

To make the overall coding simpler, this commit also slightly changes
the get_object_address representation for opclasses and opfamilies:
instead of having the AM name in the objargs array, I moved it as the
first element of the objnames array.  This enables the new code to use
objargs for the type names used by pg_amop and pg_amproc.

Reviewed by: Stephen Frost

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/a61fd5334eb1040d0dcec0368702398a5b49152c

Modified Files
--------------
src/backend/catalog/objectaddress.c          |  234 ++++++++++++++++++++------
src/backend/commands/dropcmds.c              |   24 ++-
src/backend/commands/event_trigger.c         |    2 +
src/backend/parser/gram.y                    |   43 ++---
src/include/nodes/parsenodes.h               |    2 +
src/test/regress/expected/object_address.out |   60 ++++---
src/test/regress/sql/object_address.sql      |   16 +-
7 files changed, 264 insertions(+), 117 deletions(-)