Copter: add adsb to failsafe structure and report in heartbeat to GCS

ArduCopter/Copter.h

@@ -293,6 +293,7 @@ private:
         uint8_t gcs                 : 1; // 4   // A status flag for the ground station failsafe
         uint8_t ekf                 : 1; // 5   // true if ekf failsafe has occurred
         uint8_t terrain             : 1; // 6   // true if the missing terrain data failsafe has occurred
+        uint8_t adsb                : 1; // 7   // true if an adsb related failsafe has occurred
 
         int8_t radio_counter;            // number of iterations with throttle below throttle_fs_value
 

ArduCopter/GCS_Mavlink.cpp

@@ -36,7 +36,7 @@ NOINLINE void Copter::send_heartbeat(mavlink_channel_t chan)
     uint32_t custom_mode = control_mode;
 
     // set system as critical if any failsafe have triggered
-    if (failsafe.radio || failsafe.battery || failsafe.gcs || failsafe.ekf || failsafe.terrain)  {
+    if (failsafe.radio || failsafe.battery || failsafe.gcs || failsafe.ekf || failsafe.terrain || failsafe.adsb)  {
         system_status = MAV_STATE_CRITICAL;
     }