vnc: Queue up two extra frambuffer updates

This way the server knows that the client can take up to 3 updates in a
row and doesn't have to wait for an update request after every single
frame.

src/vnc.c

@@ -207,6 +207,9 @@ int vnc_client_connect(struct vnc_client* self, const char* address, int port)
 				FALSE))
 		return -1;
 
+	SendIncrementalFramebufferUpdateRequest(client);
+	SendIncrementalFramebufferUpdateRequest(client);
+
 	return 0;
 }