AppArmor: allow QEMU to set_process_name.

https://bugzilla.redhat.com/show_bug.cgi?id=1369281

Acked-by: Christian Ehrhardt <christian.ehrhardt@canonical.co>

examples/apparmor/libvirt-qemu

@@ -21,6 +21,9 @@
   /dev/ptmx rw,
   /dev/kqemu rw,
   @{PROC}/*/status r,
+  # Per man(5) proc, the kernel enforces that a thread may
+  # only modify its comm value or those in its thread group.
+  owner @{PROC}/@{pid}/task/@{tid}/comm rw,
   @{PROC}/sys/kernel/cap_last_cap r,
 
   # For hostdev access. The actual devices will be added dynamically