support cache server max-threads on Windows with ipv6

The cache-server has a feature called max-threads that allows a large number of client connections to use a smaller thread pool. Instead of every client connection owning its own server thread, multiple connections can share the same thread.

However if the server is running on the Windows operating system using ipv6 this feature is not supported.

The code that causes this is in AcceptorImpl line 479:

      if (tmp_maxThreads > 0 && isWindows) {
        // bug #40472 and JDK bug 6230761 - NIO can't be used with IPv6 on Windows
        if (getBindAddress() instanceof Inet6Address) {
          logger.warn(
              "Ignoring max-threads setting and using zero instead due to JRockit NIO bugs.  See GemFire bug #40198");
          tmp_maxThreads = 0;
        }

Note that the warning text is wrong but the comment about the jdk bug is correct.
But according to this page: https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6230761
the jdk bug was fixed in jdk6u33 on  2012-07-30 so I think this restriction should be removed since geode no longer supports the old jdks this bug was in.