Windows: Do not remove scp from hash table on deletion

If the CM_SCACHEFLAG_DELETED flag is going to have any benefit, the
cm_scache object must not be removed from the hash table in response
to a VNOVNODE error.  Otherwise, a new cm_scache object is allocated,
the CM_SCACHEFLAG_DELETED is not found, and a new callback request
is issued to the file server which in response returns VNOVNODE.

Do this enough times and the abort threshold is triggered and then
the application becomes very unhappy with performance.

Reviewed-on: http://gerrit.openafs.org/10141
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit acad253a357c2c97fcd8f59c489ac2c7cacba7b7)

Change-Id: I6357286c93fe1b6b8efc2e1a1a83c3d46c90a716
Reviewed-on: http://gerrit.openafs.org/10157
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: Do not recycle deleted scache on refcnt 0

If the scache object with CM_SCACHEFLAG_DELETED set is recycled
then the deleted state is lost and the cache manager cannot prevent
unnecessary FetchStatus queries to the file server.

Reviewed-on: http://gerrit.openafs.org/10142
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 3f163fad55fb7e88e8206139ab1c16fe4fbe1487)

Change-Id: Ib90441f50322062e5567ee3e5fcc9074c1630c4e
Reviewed-on: http://gerrit.openafs.org/10158
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>