WINNT: Link tbutc against mtafsutil.lib

WINNT: Link tbutc against mtafsutil.lib

tbutc uses pthreads, not LWP, so link it against mtafsutil.lib (a
pthread library), and not afsutil.lib (an LWP library).

Reviewed-on: https://gerrit.openafs.org/13822
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 7a76f4dc00984d42b0535a8edbedee034ada896f)

Change-Id: I133fff53d1974658ed1fe95e48abd9779a346a4f
Reviewed-on: https://gerrit.openafs.org/13852
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>