Windows: buffer DV ranges do not work for directories

Windows: buffer DV ranges do not work for directories

In cm_MergeStatus, always set cm_scache_t.bufDataVersionLow
to the new data version because the cm_dir package does not
support version ranges.   All modified dir buffers have their
dataVersion field set to the current data version value.

Failure to update the bufDataVersionLow field can result in
B+ Trees being constructed from out of date directory information.

Reviewed-on: http://gerrit.openafs.org/6649
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
(cherry picked from commit 25142a9c2db933607507ee20e20216c635465d6d)

Change-Id: I9bdad7bed4ce76e0425adff433982b9bf35ac15f
Reviewed-on: http://gerrit.openafs.org/6827
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>