Test for "tc action mirred egress mirror" that mirrors to GRE when the underlay route points at an 802.1d bridge and packet egresses through a VLAN device. Besides testing basic connectivity, this also tests that the traffic is properly tagged. Signed-off-by: Petr Machata <petrm@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>