libceph: invalidate AUTH in addition to a service ticket

If we fault due to authentication, we invalidate the service ticket we
have and request a new one - the idea being that if a service rejected
our authorizer, it must have expired, despite mon_client's attempts at
periodic renewal.  (The other possibility is that our ticket is too new
and the service hasn't gotten it yet, in which case invalidating isn't
necessary but doesn't hurt.)

Invalidating just the service ticket is not enough, though.  If we
assume a failure on mon_client's part to renew a service ticket, we
have to assume the same for the AUTH ticket.  If our AUTH ticket is
bad, we won't get any service tickets no matter how hard we try, so
invalidate AUTH ticket along with the service ticket.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>