[libvirt] [PATCH] apparmor: implement AppArmorSetFDLabel()

During a savevm operation, libvirt will now use fd migration if qemu supports it. When the AppArmor driver is enabled, AppArmorSetFDLabel() is used but since this function simply returns '0', the dynamic AppArmor profile is not updated and AppArmor blocks access to the save file. This patch implements AppArmorSetFDLabel() to get the pathname of the file by resolving the fd symlink in /proc, and then gives that pathname to reload_profile(), which fixes 'virsh save' when AppArmor is enabled. Passes 'check' and 'syntax-check' (though po_check failed for unrelated reasons). Reference: https://launchpad.net/bugs/795800 -- Jamie Strandboge | http://www.canonical.com