In 68b726b93c11cc90 we tried to fix a mem leak. However, it
wasn't done quite well. Problem is, virNetDaemonGetServers() may
fail in which case virObjectListFreeCount() would be called with
-1 objects to free. But the number of elements is taken in
unsigned rather than signed integer.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>