pgsql: Support default ACLs in get_object_address

Support default ACLs in get_object_address

In the spirit of 890192e99af, this time add support for the things
living in the pg_default_acl catalog. These are not really "objects",
but they show up as such in event triggers.

There is no "DROP DEFAULT PRIVILEGES" or similar command, so it doesn't
look like the new representation given would be useful anywhere else, so
I didn't try to use it outside objectaddress.c. (That might be a bug in
itself, but that would be material for another commit.)

Reviewed by Stephen Frost.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/4464303405f1f886d63f8316386621cd7436c5d6

Modified Files
--------------
src/backend/catalog/objectaddress.c | 137 ++++++++++++++++++++++++--
src/backend/commands/event_trigger.c | 1 +
src/include/nodes/parsenodes.h | 1 +
src/test/regress/expected/event_trigger.out | 4 +
src/test/regress/expected/object_address.out | 17 +++-
src/test/regress/sql/event_trigger.sql | 2 +
src/test/regress/sql/object_address.sql | 7 +-
7 files changed, 158 insertions(+), 11 deletions(-)