Windows: Fix cm_serverRef ref counts

Windows: Fix cm_serverRef ref counts

Use Interlocked operations consistently

Simplify cm_ServerInsertList().  It no longer increments the
refCount on the serverRef object.  Instead it leaves the refCount
as is.  Its the caller's responsibility to add a reference if
required.

Add reference counts and hold locks in places where the
volume server list was used unprotected.

Reviewed-on: http://gerrit.openafs.org/5248
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 8f446c7463c9183d59a30343682e31ad9f85b307)

Change-Id: I0ed8ea1551527e0d62e57967da6816415a3b36b5
Reviewed-on: http://gerrit.openafs.org/5254
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>