This option was imported as part of the KAME project in r62627 (in 2000).
It was turned on unconditionally in r121472 (in 2003) and has been on ever
since. The old alternative code has bitrotted. Reap the dead code.
Reported by: Ján Sučan <jansucan@gmail.com>
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20938
(aka RFC2292bis). Though I believe this commit doesn't break
backward compatibility againt existing binaries, it breaks
backward compatibility of API.
Now, the applications which use Advanced Sockets API such as
telnet, ping6, mld6query and traceroute6 use RFC3542 API.
Obtained from: KAME
