Make sure apparmor is started before libvirtd

If apparmor security driver is enabled in either qemu or lxc
driver configuration and libvirtd starts before AppArmor, it will fail.

daemon/libvirtd.service.in

@@ -9,6 +9,7 @@ Before=libvirt-guests.service
 After=network.target
 After=dbus.service
 After=iscsid.service
+After=apparmor.service
 Documentation=man:libvirtd(8)
 Documentation=http://libvirt.org