8199931: java/net/MulticastSocket/UnreferencedMulticastSockets.java fails with "incorrect data received"

Backport-of: f367eb8

Author: RealCLanger

test/jdk/java/net/MulticastSocket/UnreferencedMulticastSockets.java

@@ -120,6 +120,7 @@ public static void main(String args[]) throws Exception {
         thr.start();
 
         MulticastSocket client = new MulticastSocket(0);
+        System.out.printf("  client bound port: %d%n", client.getLocalPort());
         client.connect(svr.getHost(), svr.getPort());
         pendingSockets.add(new NamedWeak(client, pendingQueue, "clientMulticastSocket"));
         extractRefs(client, "clientMulticastSocket");