Log Message:
databases/postgresql(-client): Revert most of last commit

After discussing gcc47 build problems with postgresql developers, it
became apparent that the error was unique to DragonFly.  It turns out
that DragonFly was using an older offsetof macro instead of the builtin
version provided by GCC.

Fixing the offsetof macro on DragonFly allowed the pre-patched psgsql 91
to build without issue.  While the previous patches certainly don't hurt
anything, they are being removed to ease future maintenance.

The warning suppression fix is still valid, so the change to the pgsql
client makefile is being left in place.