Windows: AFSLocateNameEntry Backup Volume Change

When AFSLocateNameEntry() calls AFSBackupEntry() in the name array it is
possible that the DirectoryCB returned belongs to a different VolumeCB.
If so, pCurrentVolume must be updated and reference counts must be
adjusted.

Change-Id: I9fcd30374b20f2e1c214a019feeab55c30ce9666
Reviewed-on: http://gerrit.openafs.org/9465
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>