Ensure libvirt_lxc process loads the live XML config

Ensure libvirt_lxc process loads the live XML config

Currently the libvirt_lxc process uses VIR_DOMAIN_XML_INACTIVE
when loading the XML for the container. This means it loses
any dynamic data such as the, just allocated, SELinux label.

Further there is an inconsistency in the libvirt LXC driver
whereby it saves the live config XML and then later overwrites
the file with the live status XML instead. Add a comment about
this for future reference.

* src/lxc/lxc_controller.c: Remove VIR_DOMAIN_XML_INACTIVE
  when loading XML
* src/lxc/lxc_driver.c: Add comment about inconsistent
  config file formats

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>