Windows: Perform rename to self check earlier

Windows: Perform rename to self check earlier

In AFSSetRenameInfo(), the rename to itself check was performed
after the name collision check.  Move the check earlier in the
routine to ensure that we catch the no-op before any real work
is done.

Change-Id: I580dd9958a259d4a1819c6bd882dae8067d2853d
Reviewed-on: http://gerrit.openafs.org/6692
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>