- With IPv6->IPv4 translation, fix a bug that a FTP PORT command ends   in failure when source port number is not translated.
- With IPv6->IPv4 translation, fix a bug that a FTP PORT command ends
  in failure when source port number is not translated.

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