Windows: avoid recursive cm_CheckOfflineVolume

Windows: avoid recursive cm_CheckOfflineVolume

Add a new cm_req_t flag CM_REQ_OFFLINE_VOL_CHK which is used
to prevent cm_Analyze() from performing recursive
cm_CheckOfflineVolume operations that will exhaust the stack.

Reviewed-on: http://gerrit.openafs.org/4240
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit 11ad1e467f9708f12fe09228cbb827b8f4e1225b)

Change-Id: I3385d7b5a90e77ba8d6c87b9f29f39b62c17bb23
Reviewed-on: http://gerrit.openafs.org/4314
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>