Code Review 6882910: Unexplained lack of IP4 network ability when transparent IP6 to IP4 is disabled.

[Chris Hegarty]

Alan,

Don't assume sockets will default to dual stack, explicitly set 
IPV6_V6ONLY to 0. Apparently some Linux distros ship with 
net.ipv6.bindv6only=1 restricting sending and receiving to IPv6 packets 
only. Changes both net and nio code.

Webrev:
  http://cr.openjdk.java.net/~chegar/6882910/webrev.00/webrev/

Thanks,
-Chris.