Windows: add parent FID to cm_GetSCache

Windows: add parent FID to cm_GetSCache

When a cm_scache_t object is created in 98% of the time, the
parent FID is known to the cache manager.  Normally the cache
manager will obtain the parent info from the AFSFetchStatus
structure but if the user credentials do not permit status info
to be obtained from the file server the parent info will be unavailable.

Having the parent directory FID is useful for debugging but can
also be used to check the user's access rights on the parent directory.

Change-Id: I262345bc686392a4edef4c627182a8a67a392aa2
Reviewed-on: http://gerrit.openafs.org/6993
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>