[Net] ENet poll now only service the connection once.

It used to call `enet_host_service` until all events were consumed, but
that also meant constantly polling the connection leading to potentially
unbounded processing time.

It now only service the connection once, and instead consumes all the
retrieved events via `enet_host_check_events`.

modules/enet/networked_multiplayer_enet.cpp

@@ -217,20 +217,23 @@ void NetworkedMultiplayerENet::poll() {
 
 	_pop_current_packet();
 
+	if (!host || !active) { // Might be disconnected
+		return;
+	}
+
 	ENetEvent event;
-	/* Keep servicing until there are no available events left in queue. */
-	while (true) {
-		if (!host || !active) { // Might have been disconnected while emitting a notification
-			return;
-		}
+	int ret = enet_host_service(host, &event, 0);
 
-		int ret = enet_host_service(host, &event, 0);
+	if (ret < 0) {
+		ERR_FAIL_MSG("Enet host service error");
+	} else if (ret == 0) {
+		return; // No events
+	}
 
-		if (ret < 0) {
-			// Error, do something?
-			break;
-		} else if (ret == 0) {
-			break;
+	/* Keep servicing until there are no available events left in the queue. */
+	do {
+		if (!host || !active) { // Check again after every event
+			return;
 		}
 
 		switch (event.type) {
@@ -436,7 +439,7 @@ void NetworkedMultiplayerENet::poll() {
 				// Do nothing
 			} break;
 		}
-	}
+	} while (enet_host_check_events(host, &event) > 0);
 }
 
 bool NetworkedMultiplayerENet::is_server() const {