More fun with IPv6 Listen statements.

- Remove the default_family declaration as it is no longer used.
- Fix segfault if checking NULL sa->hostname.
- Cycle through the bind_addr list if we get an error creating an IPv6 socket
  and we're IPv6 enabled and the binding address is NULL.  The odds are that
  we just can't support IPv6.  (The twist is that apr_sockaddr_info_get should
  return bind_addr's for IPv6 and IPv4.  This strikes me as slightly more
  elegant than the find_default_family hack.)

This should get us working on Linux and Netware again.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100994 13f79535-47bb-0310-9956-ffa450edef68