vlserver: Add auditing to some more RPC's

A future commit will conditionally restrict access to these RPC's.
Auditing will allow debugging and monitoring of this feature.

Reviewed-on: http://gerrit.openafs.org/10939
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 900427ecac4bde5ef78ae9fc86f9237552cc1dd4)

Change-Id: Id140855220522ebfe560e1023f3b68acb67e82e9
Reviewed-on: http://gerrit.openafs.org/10946
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>