When spawning 'init' in the container, set

  LIBVIRT_LXC_UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
  LIBVIRT_LXC_NAME=YYYYYYYYYYYY

to allow guest software to detect & identify that they
are in a container

* src/lxc/lxc_container.c: Set LIBVIRT_LXC_UUID and
  LIBVIRT_LXC_NAME env vars