vlserver: limit use of regex to admins always

vlserver: limit use of regex to admins always

allow regexes only if the querying user is a superuser.
if the superuser uses up all the resources, well, they could just do
whatever damage directly anyway. means even in unrestricted mode
we are not vulnerable

Reviewed-on: http://gerrit.openafs.org/11968
Reviewed-by: Daria Brashear <shadow@your-file-system.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 049323e7e03c64f534a73ff452d218f19d5b8132)

Change-Id: I1e3f11bd14b071be69eb6e00c26ea2209596c82a
Reviewed-on: http://gerrit.openafs.org/11975
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>