Windows: Do not call buf_ClearRDRFlag unlink/rmdir

Windows: Do not call buf_ClearRDRFlag unlink/rmdir

When processing unlink and remdir operations initiated by the
SMB stack do not call  buf_ClearRDRFlag.  The redirector upon
receiving the AFS_INVALIDATE_DELETE call will cancel outstanding
extent operations, mark the FCB deleted, and tear down any held
extents.

Change-Id: I5203dbe5489fcfd0a1c871c3e7aa6aa1a7d65e9a
Reviewed-on: http://gerrit.openafs.org/8218
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>