Windows: avoid duplicate volume update queries

Windows: avoid duplicate volume update queries

If multiple volume update queries have stacked up in
cm_UpdateVolumeLocation() and the active query failed,
do not re-issued the blocked queries.  Instead, prevent new
queries for 60 seconds and fail those that blocked during
the active query.

Change-Id: Ic3f55ae08da36900fc8c7a89b6487ae53f381eb3
Reviewed-on: http://gerrit.openafs.org/5296
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>