apparmor: allow to call vhost-user-gpu

Configuring vhost-user-gpu like:
    <video>
      <driver name='vhostuser'/>
      <model type='virtio' heads='1'/>
    </video>
Triggers an apparmor denial like:
    apparmor="DENIED" operation="exec" profile="libvirtd"
    name="/usr/lib/qemu/vhost-user-gpu" pid=888257 comm="libvirtd"
    requested_mask="x" denied_mask="x" fsuid=0 ouid=0

This helper is provided by qemu for vhost-user-gpu and thereby being
in the same path as qemu_bridge_helper. Due to that adding a rule allowing
to call uses the same path list.
Reviewed-by: NJim Fehlig <jfehlig@suse.com>
Signed-off-by: NChristian Ehrhardt <christian.ehrhardt@canonical.com>

src/security/apparmor/usr.sbin.libvirtd.in

@@ -86,6 +86,7 @@ profile libvirtd @sbindir@/libvirtd flags=(attach_disconnected) {
   /usr/{lib,lib64}/xen-common/bin/xen-toolstack PUx,
   /usr/{lib,lib64}/xen/bin/* Ux,
   /usr/lib/xen-*/bin/libxl-save-helper PUx,
+  /usr/{lib,lib64,lib/qemu,libexec}/vhost-user-gpu PUx,
 
   # Required by nwfilter_ebiptables_driver.c:ebiptablesWriteToTempFile() to
   # read and run an ebtables script.