pgsql: Add missing support for removing foreign data wrapper / server p

Add missing support for removing foreign data wrapper / server privileges
belonging to a user at DROP OWNED BY. Foreign data wrappers and servers
don't do anything useful yet, which is why no-one has noticed, but since we
have them, seems prudent to fix this. Per report from Chetan Suttraway.
Backpatch to 9.0, 8.4 has the same problem but this patch didn't apply
there so I'm not going to bother.

Branch
------
REL9_0_STABLE

Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=533073cf2321bb9fd3ec983443e41b7040f2771b

Modified Files
--------------
src/backend/catalog/aclchk.c |    6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)