add a comment about in6_pcbconnect() bug in IPv4 mapped address case (local port allocation does not consult IPv4 port number space).
add a comment about in6_pcbconnect() bug in IPv4 mapped address case
(local port allocation does not consult IPv4 port number space).

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