Windows: Do not probe new servers from cm_UpdateVolumeLocation

Windows: Do not probe new servers from cm_UpdateVolumeLocation

cm_NewServer() can result in a call to cm_UpdateVolumeLocation()
if a server probe is performed.   In order to avoid recursive
calls to cm_UpdateVolumeLocation() do not probe new servers from
within cm_UpdateVolumeLocation().

Change-Id: Icdb8efe030ae3e1f714ca72ad741bd38c692697f
Reviewed-on: http://gerrit.openafs.org/4922
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>