Windows: Fix out of range pointer validation

The ACL, Stat, and Volume pointer validation checks did not take
into account that NULL is a valid pointer value.  As a result the
cache validation failed.

Reviewed-on: http://gerrit.openafs.org/10453
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit dbedd62b7cb6c2203afea72d6f0ea32b0d623b10)

Change-Id: Ic76a04565856e792304d2c33da14a10e6ed5d244
Reviewed-on: http://gerrit.openafs.org/10468
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: cm_FindVolumeByFID

cm_GetVolumeByFID() does not query the vldb if the volume group
is not known to the cache manager.   cm_FindVolumeByFID() is to
be used in cases where the volume group data must be known for the
operation to successfully complete.

Reviewed-on: http://gerrit.openafs.org/10465
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 0570d13a62c6f9416bed4fcbab5cf49a45b4dcc1)

Change-Id: I29a9c9fdd277789483cd5809b088c1f6441d344e
Reviewed-on: http://gerrit.openafs.org/10469
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>