Windows: Redesign of server preferences

Windows: Redesign of server preferences

Server rankings should be composed from three values:

 1. administrative preferences

 2. network address locality

 3. peer performance (rtt and congestion window)

This ensures that local subnet servers are always
preferred.

Add a new rank for down servers so they are always
sorted las in cm_serverRef lists.

Change-Id: Id00e151fc1acd65db558571e6a3a0e7cfbf3c6ca
Reviewed-on: http://gerrit.openafs.org/7757
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>