Windows: correct cm_buf use of Head/Tail queues

Windows: correct cm_buf use of Head/Tail queues

The buffer free list least recently used queue has both
head and tail points.  Use the proper versions of the queue
mgmt functions and do not handle edge cases as special cases.

Reviewed-on: http://gerrit.openafs.org/5354
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit 537592f6bbda0c659c25ae7068f50504e2a5e116)

Change-Id: I0d5afaf59895f34ced739f4626a351fe41186008
Reviewed-on: http://gerrit.openafs.org/6030
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>