RFR: 8211842 IPv6_supported wrongly returns false when unix domain socket is bound to fd 0

[Michael McMahon]

Could I get the following fix reviewed please?
The fix is pretty simple, but the test a bit more involved
since the issue occurs when the JVM is launched in unusual circumstances
where its stdin,out,err are connected to a UNIX domain socket.
This occurs when java is launched by a node.js or Python script.

http://cr.openjdk.java.net/~michaelm/8211842/webrev.1/

Thanks,

Michael