do not overwrite rcvif if traffic is non-IPv4. it breaks IPv6 scoped address handling.
do not overwrite rcvif if traffic is non-IPv4.
it breaks IPv6 scoped address handling.

XXX rcvif manipulation is for bridges.  with bridging support, *now* we
may really need to consider 1-to-n mapping between link and interface.

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame