Fix Hil build on 2560

git-svn-id: https://arducopter.googlecode.com/svn/trunk@2961 f9c3cf11-9bcb-44bc-f272-b75c42450872

ArduCopterMega/ArduCopterMega.pde

@@ -175,6 +175,9 @@ static AP_Int8                *flight_modes = &g.flight_mode1;
 	AP_GPS_HIL              g_gps_driver(NULL);
 	AP_Compass_HIL          compass; // never used
 	AP_IMU_Shim             imu; // never used
+	#ifdef OPTFLOW_ENABLED
+		AP_OpticalFlow_ADNS3080 optflow;
+	#endif
     static int32_t          gps_base_alt;
 #else
 	#error Unrecognised HIL_MODE setting.
@@ -1578,4 +1581,4 @@ static void auto_throttle()
 	invalid_throttle = false;
 
 	//Serial.printf("wp:%d, \te:%d \tt%d \t%d\n", (int)next_WP.alt, (int)altitude_error, nav_throttle, g.rc_3.servo_out);
-}
+}