Use start_timer_nodelay() in protocols which rely on the retry timer

to generate the initial transmission; this cuts off around 0.3s per
instantiated connection.

src/net/tcp.c

@@ -232,7 +232,7 @@ static int tcp_open ( struct xfer_interface *xfer, struct sockaddr *peer,
 		goto err;
 
 	/* Start timer to initiate SYN */
-	start_timer ( &tcp->timer );
+	start_timer_nodelay ( &tcp->timer );
 
 	/* Attach parent interface, transfer reference to connection
 	 * list and return