Windows: Avoid file server rpcs on deleted files

Windows: Avoid file server rpcs on deleted files

If a file has been deleted, do not attempt to issue RPCs
to the file server in response to AFS redirector extent processing.
All RPCs will fail with VNOVNODE which will in turn trigger invalidation
requests to the AFS redirector which can deadlock.

Change-Id: I85b6b4a0ce619e54df648163392be93761f709f0
Reviewed-on: http://gerrit.openafs.org/6514
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>