Windows: define new event log messages for cm_Analyze VBUSY, VRESTARTING, etc.

Windows: define new event log messages for cm_Analyze VBUSY, VRESTARTING, etc.

Add MSG_SERVER_REPORTS_VBUSY, MSG_SERVER_REPORTS_VRESTARTING,
MSG_ALL_SERVERS_BUSY, MSG_ALL_SERVERS_OFFLINE,
and MSG_ALL_SERVERS_DOWN.

Add event message throttling.  Only permit one copy of a message
to be generated every five seconds if the message will duplicate
the prior message.  This often occurs when a server or volume becomes
inaccessible and there were a large number of requests queued on it.

Integrate these new messages into cm_Analyze processing for VBUSY,
VRESTARTING, ALLDOWN, ALLOFFLINE, and ALLBUSY errors.

LICENSE MIT

Change-Id: Ib30595ded23724810e294133fa75873e20ffbf0b
Reviewed-on: http://gerrit.openafs.org/1762
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>