mounted-dev.conf won't be running that in container's userspace as it
previously would have, so make sure that all the devices it would have
created (other than ones which lxc later finagles) get created.
To achieve this, we have to first mount /dev, then run MAKEDEV, then
run setup_autodev to populate the rest of /dev.

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1075717

Changelog:
  v2: Use INFO rather than ERROR when makedev fails, since we won't stop the container boot.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>