Windows: replace lana_OnlyLoopback() calls

lana_OnlyLoopback() relies upon Netbios over TCP being enabled but
Netbios over TCP is not officially supported on Vista and above.
Replace all lana_OnlyLoopback() calls with a test on the number of
network interfaces as computed by syscfg_GetIFInfo().   That list
excludes loopback interfaces.

Change-Id: I22d952f1487734ead02335108377bc404baa6024
Reviewed-on: http://gerrit.openafs.org/11444
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: introduce cm_MarkServerDown

Consolidate the operations necessary to mark a server down into a
new routine cm_MarkServerDown()

Change-Id: I9f70752498600046d677686c212c3adf3e810bde
Reviewed-on: http://gerrit.openafs.org/11445
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>