lxclock: move container locks into /run/lock

Currently the lxc API mutexes configuration file read/writes with a
lock called $lxcpath/locks/$lxcname.  This fails if the container
is on a rofs.

This patch moves those locks under /run/lock/lxc.

The $lxcpath/$lxcname/partial file is not moved - if you can't
create it, you probably can't create the container either.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>