Windows: Add CM_MERGEFLAG_CACHE_BYPASS

If a store operation is performed direct to the file server
bypassing the AFSCache, call cm_MergeStatus() with
CM_MERGEFLAG_CACHE_BYPASS to ensure that the valid version
numbers for the cm_scache_t object are incremented appropriately.
After a cache bypass occurs, only buffers with the current
data version number are valid since the cached data will be
incomplete.

Change-Id: I9438f8c9759407de69ab894df4f6fe91027a4b94
Reviewed-on: http://gerrit.openafs.org/8964
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>