Test that resolved neighbours for IPv4 broadcast addresses are
unaffected by the configuration of matching broadcast routes, whereas
unresolved neighbours are invalidated.

Without previous patch:

 # ./fib_tests.sh -t ipv4_bcast_neigh

 IPv4 broadcast neighbour tests
     TEST: Resolved neighbour for broadcast address                      [ OK ]
     TEST: Resolved neighbour for network broadcast address              [ OK ]
     TEST: Unresolved neighbour for broadcast address                    [FAIL]
     TEST: Unresolved neighbour for network broadcast address            [FAIL]

 Tests passed:   2
 Tests failed:   2

With previous patch:

 # ./fib_tests.sh -t ipv4_bcast_neigh

 IPv4 broadcast neighbour tests
     TEST: Resolved neighbour for broadcast address                      [ OK ]
     TEST: Resolved neighbour for network broadcast address              [ OK ]
     TEST: Unresolved neighbour for broadcast address                    [ OK ]
     TEST: Unresolved neighbour for network broadcast address            [ OK ]

 Tests passed:   4
 Tests failed:   0
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>