8243408: Inconsistent Exceptions are thrown by MulticastSocket when sending a DatagramPacket to port 0

This fix adds a check for port == 0 to MulticastSocket's 2-arg send method to ensure a consistent exception is thrown across platforms

Reviewed-by: dfuchs

src/java.base/share/classes/java/net/MulticastSocket.java

@@ -797,6 +797,9 @@ public class MulticastSocket extends DatagramSocket {
                             // set the ttl
                             getImpl().setTTL(ttl);
                         }
+                        if (packetPort == 0) {
+                            throw new SocketException("Can't send to port 0");
+                        }
                         // call the datagram method to send
                         getImpl().send(p);
                     } finally {