Fix for bug #8167 in PostgreSQL 9.2.4 that causes failed inserts on Macs.

Details of bug: http://www.postgresql.org/message-id/E1UcmpR-0004nn-2i@wrigleys.postgresql.org

The bug has been fixed upstream and will presumably be included
in future releases. The fix commit is below; we have to slightly
modify their patch to work around a whitespace problem in applying it.
https://github.com/postgres/postgres/commit/6563fb2b45146852601e63828308fe04fb03b9e9