Windows: Adjust setting of VERIFY_DATA flag

If the CcPurge operation fails or cannot be performed, in addition
to setting the purge on close flag, set the verify data flag.  This
ensures that the next attempt to access the file will retry the
purge.

Reviewed-on: http://gerrit.openafs.org/10217
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 2a1035a49bfb67152f14b500d9c614e4df1013c8)

Change-Id: Iccaa3ae61700ae943c9267788ba0595d981a6f11
Reviewed-on: http://gerrit.openafs.org/10222
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>