Forward port security patch for CAN-2003-0254 from 2.0.

SECURITY [CAN-2003-0254]: Fixed a bug in ftp proxy causing denial
of service when target host is IPv6 but proxy server can't create
IPv6 socket.  Fixed by the reporter.  [Yoshioka Tsuneo
<tsuneo.yoshioka@f-secure.com>]


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100516 13f79535-47bb-0310-9956-ffa450edef68