Windows: Avoid deadlock during pending delete cleanup

Release the Fcb resource and clear the AFS_DIR_ENTRY_PENDING_DELETE
flag prior to the AFSProcessRequest(AFS_REQUEST_TYPE_CLEANUP_PROCESSING)
if a delete is pending during cleanup of the last FCB open handle.

Failure to do so results in an out of order lock acquisition when
the parent object info tree lock is acquired after the AFSProcessRequest()
call to the service completes.

Change-Id: Id1c770b3dfe669d6804276bbe832af2d215c72dc
Reviewed-on: http://gerrit.openafs.org/11425
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>