message: calibration: don't calibrate without autopilot
diff: @@ -23,6 +23,7 @@ TEST(HardwareTest, GyroCalibration)
  // Wait for system to connect via heartbeat.
  std::this_thread::sleep_for(std::chrono::seconds(2));
  System &system = dc.system();
  + ASSERT_TRUE(system.has_autopilot());
  auto calibration = std::make_shared<Calibration>(system);
  @@ -46,6 +47,7 @@ TEST(HardwareTest, AccelerometerCalibration)
  // Wait for system to connect via heartbeat.
  std::this_thread::sleep_for(std::chrono::seconds(2));
  System &system = dc.system();
  + ASSERT_TRUE(system.has_autopilot());
  auto calibration = std::make_shared<Calibration>(system);
  @@ -71,6 +73,7 @@ TEST(HardwareTest, MagnetometerCalibration)
  System &system = dc.system();
  auto calibration = std::make_shared<Calibration>(system);
  + ASSERT_TRUE(system.has_autopilot());
  bool done = false;
  