Windows: AFSLocateNameEntry OutVolumeCB can be NULL

It is possible for the AFSLocateNameEntry OutVolumeCB parameter
to be assigned a NULL value upon return.   Handle it in the callers.

Reviewed-on: http://gerrit.openafs.org/9464
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit c9846c9e804299de41a298adf69c9c0666d8ec85)

Change-Id: Ief17ed8a0d4f73cb20931dcd6f20355faafb33d3
Reviewed-on: http://gerrit.openafs.org/9558
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
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.

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>
(cherry picked from commit 540a73dc18bfacebc72dfac2e3c3d9f06c87e18f)

Change-Id: I53abb70f1ca887874c0311f86f5069d57908c172
Reviewed-on: http://gerrit.openafs.org/9559
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>