reject IPv6 traffic, with IPv4 mapped address in the header.
reject IPv6 traffic, with IPv4 mapped address in the header.

the code was removed once, but in a second thought, it makes more sense
as we cannot live in SIIT environment anyways.  see comments for detail.

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