WINNT: Link butc against audit

WINNT: Link butc against audit

Since commit c43169fd (OPENAFS-SA-2018-001 Add auditing to butc server
RPC implementations), butc references symbols from audit. So add audit
to our libraries to link against, so we can link butc on WINNT.

Reviewed-on: https://gerrit.openafs.org/13818
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit e4b689e8c7cb39b72854dd38b6a92134591c8bca)

Change-Id: Ib27755730178afbbd85e3aad265c1f956b3785ef
Reviewed-on: https://gerrit.openafs.org/13850
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>