ubik: SVOTE_Beacon should hold the DB lock for CheckTid

ubik: SVOTE_Beacon should hold the DB lock for CheckTid

Reviewed-on: https://gerrit.openafs.org/4262
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 5548f6540557795ded65a52c7066839c5eef468f)

Change-Id: I0d4a4d5e796bc6cb731f00db34cc0776f746ca85
Reviewed-on: https://gerrit.openafs.org/12516
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>