NetPlayServer: Close the socket when we're done with it

This would allow a new socket to be created with the same port after
we close it. However, we can't reuse it immediately because of the TCP
TIME-WAIT state.

Source/Core/Core/Src/NetPlayServer.cpp

@@ -26,6 +26,7 @@ NetPlayServer::~NetPlayServer()
 	{
 		m_do_loop = false;
 		m_thread.join();
+		m_socket.Close();
 	}
 
 #ifdef USE_UPNP