Windows: AFSLocateNameEntry double free Volume RefCount

If AFSBuildMountPointTarget fails when called from AFSLocateNameEntry
the pCurrentVolume reference count will have been freed even though
the pointer has not been updated.   If the failure is
STATUS_OBJECT_NAME_NOT_FOUND and AFSLocateNameEntry was called
by AFSCreateCommon, the Volume reference count will be freed twice.

Reviewed-on: http://gerrit.openafs.org/9069
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 028258e6393bd76df0944dc77266bfba176ada73)

Change-Id: I84b8f82929a3349fb2a08ac58c19f37e7813091e
Reviewed-on: http://gerrit.openafs.org/9073
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>