RFR(XS): 8229912: [TESTBUG] java/net/Socks/SocksIPv6Test fails without IPv6

[Nick Gasson]

Hi,

Bug: https://bugs.openjdk.java.net/browse/JDK-8229912
Webrev: http://cr.openjdk.java.net/~ngasson/8229912/webrev.0/

This test should be skipped if IPv6 is disabled on the host, and it
already has a shouldRun field to support this. But at the moment the
the setUp() method will throw inside HttpServer.create() when it's
passed an IPv6 address on a system with IPv6 disabled. Fix is to check
shouldRun in setUp and return immediately if it's false.

Thanks,
Nick