[libvirt] AUTHORS update (was: [PATCH] Fix security context references in DAC code)

I'm also pushing a followup patch to update AUTHORS with seven recent patch contributors (to avoid posting raw email addresses for spammers to harvest, I won't post that patch to the list unless specifically requested). I think that qualifies as obvious, using the formula: git shortlog $(git log -1 --format=%H AUTHORS).. | grep -v "^ " and adding all authors that aren't already listed.