Windows: KFW_AFS_klog() changes

Windows: KFW_AFS_klog() changes

If an explicit 'realm' is specified as input:

 a. Do not duplicate a request for afs/cellname@REALM if the
    explicit realm matches the realm of the client principal.

 b. If afs/cellname@REALM fails, request afs@REALM for the
    explicit realm.

This patchset does not apply to master due to Kerberos Compatibility
SDK conversion.

Reviewed-on: http://gerrit.openafs.org/8773
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit f9e9d9aebf2f671b099253ec847b0dd32ce5c686)

Change-Id: I0cbf8f9a540159b5169e4cdf409dc7e875527d77
Reviewed-on: http://gerrit.openafs.org/8776
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>