Fix posix shutdown code

socketio_posix.cpp

@@ -127,7 +127,7 @@ server_socket::server_socket(int _port) : port_(_port){
 	}
 }
 void server_socket::close(){
-	shutdown(server_fd);
+	shutdown(server_fd,SHUT_RDWR);
 }
 cppsocket server_socket::accept_connection(){
 	int new_socket;