systemd: Do not race on RuntimeDirectory

systemd: Do not race on RuntimeDirectory

Different unit instances create and destroy the same RuntimeDirectory.
This leads to running instances where the status file (and possibly
more runtime data) is no longer accessible.

So do not handle this in unit files but provide a tmpfiles.d
configuration and let systemd-tmpfiles do the work.
Nobody will (unintentionally) delete the directories and its content.
As /run is volatile we do not have to care about cleanup.

Signed-off-by: Christian Hesse <mail@eworm.de>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <20170124143947.27385-2-list@eworm.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13939.html
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit 3de7be7b17de879a78eea4afe4c918c6104c635d)