[PATCH] remove redundant ownership checks

It is a cleanup patch apart from SELinux and security framework.

Now, EnableDisableRule() checks ownership of the relation which
owns the rewrite rule to be enabled/disabled.

But it has the following call path, and this check is already done
in the ATPrepCmd().
ATExecCmd() -> ATExecEnableDisableRule()  -> EnableDisableRule()

This patch removes redundant permission checks.
No need to check same things twice.

Also see the related discussions: http://archives.postgresql.org/pgsql-hackers/2009-09/msg01593.php
http://archives.postgresql.org/pgsql-hackers/2009-09/msg01839.php
http://archives.postgresql.org/pgsql-hackers/2009-09/msg01840.php

Thanks,
-- 
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai@ak.jp.nec.com>