Bug#789796: Backported systemd upstream fix

Hi, we were running into this problem when using unprivileged LXC containers, after applying the upstream patch this bug did not occur anymore.

Bug#818978: systemd crashes in lxc on container stop

Hi, backporting the upstream fix [0] from systemd 219 doesn't seem to resolve the issue, but Stéphane Grabers patches [1] do so. All patches have been tested with current LXC/LXD/lxcfs 2.0.0 RCs with debian jessie as host/guest system. [0]