GCS_MAVLink: send HYGROMETER_SENSOR message if data available

libraries/GCS_MAVLink/GCS.h

@@ -27,6 +27,7 @@
 #include <AP_OpenDroneID/AP_OpenDroneID.h>
 #include <AP_Mount/AP_Mount.h>
 #include <AC_Fence/AC_Fence.h>
+#include <AP_Airspeed/AP_Airspeed_config.h>
 
 #include "ap_message.h"
 

libraries/GCS_MAVLink/ap_message.h

@@ -81,6 +81,7 @@ enum ap_message : uint8_t {
     MSG_MCU_STATUS,
     MSG_UAVIONIX_ADSB_OUT_STATUS,
     MSG_ATTITUDE_TARGET,
+    MSG_HYGROMETER,
     MSG_AUTOPILOT_STATE_FOR_GIMBAL_DEVICE,
     MSG_LAST // MSG_LAST must be the last entry in this enum
 };