Windows: only flush buffers on shutdown if running

Windows: only flush buffers on shutdown if running

If a service shutdown message is received prior to the
service entering the running state, do not attempt to
buf_CleanAndReset() because the required data structures
and locks are not initialized.

Reviewed-on: http://gerrit.openafs.org/5733
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
(cherry picked from commit 9743f5729d1a55513e861bb1334599a8e597de6b)

Change-Id: I2bda1c4a538c83595f2d60ad4661c7e6865c5fc3
Reviewed-on: http://gerrit.openafs.org/6041
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>