Drivers load running persistent and transient domain configs before
inactive persistent domain configs, however only the latter would set a
domain's autostart flag. This mismatch between the loaded and on-disk
state could later cause problems with "virsh autostart":

  # virsh autostart example
  error: Failed to mark domain example as autostarted
  error: Failed to create symlink '/etc/libvirt/qemu/autostart/example.xml to '/etc/libvirt/qemu/example.xml': File exists

This patch ensures the autostart flag is set correctly even when the
domain is already defined.

Fixes:

  https://bugzilla.redhat.com/show_bug.cgi?id=632100
  https://bugzilla.redhat.com/show_bug.cgi?id=675319Signed-off-by: NMichael Chapman <mike@very.puzzling.org>