Windows: AFSDeleteObjectInfo InterlockedCompareExchangePointer

Correct the third parameter passed to InterlockedCompareExchangePointer
in AFSDeleteObjectInfo() which prevented *ppObjectInfo from being set
to NULL.

Reviewed-on: http://gerrit.openafs.org/9689
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit bc1b79d030eb9e2b9076edb90cce7807dae5d949)

Change-Id: I59d06ac477812f749689cc4294200850dce32878
Reviewed-on: http://gerrit.openafs.org/9718
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>