/var/run may reside on a tmpfs and we fail to create the PID file if
/var/run/lxc does not exist.

Since commit 0a8addc1, the lxc driver's state directory isn't
automatically created before starting a domain. Now, the lxc driver
makes sure the state directory exists when it initializes.
Signed-off-by: NLubomir Rintel <lkundrak@v3.sk>