Tracker: make setting of home boolean in preparation for sanity checks

AntennaTracker/GCS_Mavlink.h

@@ -28,8 +28,8 @@ protected:
         return 0; // what if we have been picked up and carried somewhere?
     }
 
-    bool set_home_to_current_location(bool lock) override { return false; }
+    bool set_home_to_current_location(bool lock) override WARN_IF_UNUSED { return false; }
-    bool set_home(const Location& loc, bool lock) override { return false; }
+    bool set_home(const Location& loc, bool lock) override WARN_IF_UNUSED { return false; }
 
 private:
 

AntennaTracker/system.cpp

@@ -156,7 +156,9 @@ void Tracker::set_home(struct Location temp)
     // check EKF origin has been set
     Location ekf_origin;
     if (ahrs.get_origin(ekf_origin)) {
-        ahrs.set_home(temp);
+        if (!ahrs.set_home(temp)) {
+            // ignore error silently
+        }
     }
 }