When someone does 'systemctl enable libvirtd.service' we should
also enable virtlockd.socket/virtlogd.socket, so that they can
be auto-activated if libvirtd tries to access the sockets.

Without this, people have to manually enable the units themselves
via 'systemctl enable virtdlogd.socket'.

This also ensures that if distros uses  'systemctl preset' for
enabling 'libvirtd.service', then the virtdlogd.socket gets
enabled without having to wait for the distro to update their
presets file.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>