[libvirt] Various apparmor related changes (part 1)

Over the years there have been a bunch of changes to the apparmor profiles and/or virt-aa-helper which have been carried in Debian/Ubuntu but never made it upstream. In an attempt to clean this up and generally improve the apparmor based environments, we (Christian and I) went over the changes, cleaned out cruft as much as possible and would be sending out hunks of changes to this list for upstream inclusion. I hope doing multiple but smaller rounds of submissions will make it simpler to get those reviewed and hopefully accepted. This first batch contains a mix of changes from Debian and Ubuntu. Thanks, Stefan