Windows: dir buffers out of date - mark them as such

Windows: dir buffers out of date - mark them as such

if cm_CheckForSingleDirChange() fails, mark the cm_scache_t
bufDataVersionLow as the current data version so that old directory
buffers are discarded.

Reviewed-on: http://gerrit.openafs.org/6498
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 e77b6858ee889ec9e4e3fe3bb62c23b1c1f5727f)

Change-Id: I8b149d3655c249fc3ea034d179b919f4370f19a2
Reviewed-on: http://gerrit.openafs.org/6821
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>