Make vrouter coexist with Linux bridge (and not coexist with OVS).

Bug 1338900

Change-Id: Ie2455a070acd03f55d0a920a4495fe2fded1ab74
BUG:1336717
Do trap + forward the packet when the packet arrives from an ECMP source
that was different from the destination of the forward flow

[ forward port into mainline ]

Change-Id: If9283fde17f4353cd483b0f5b87100e82a4c8fca