Windows: AFSCleanup re-organization

Windows: AFSCleanup re-organization

Reorganize the activities of the AFSCleanup() for File FCBs
so that the Fcb Resource can be dropped prior to issuing the
cleanup request to the cache manager.   The cache manager can
block for a long period of time while flushing data and holding
the Fcb resource blocks all subsequent CreateFile requests.

Change-Id: Ieaf3653ebf487670bce1043e73be093eb77a8736
Reviewed-on: http://gerrit.openafs.org/8307
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>