Copter: don't set takeoff expected in throw mode

especially bad for dropping off a bridge

ArduCopter/baro_ground_effect.cpp

@@ -31,8 +31,11 @@ void Copter::update_ground_effect_detector(void)
 
     // takeoff logic
 
-    // if we are armed and haven't yet taken off
-    if (motors->armed() && ap.land_complete && !gndeffect_state.takeoff_expected) {
+    if (flightmode->mode_number() == Mode::Number::THROW) {
+        // throw mode never wants the takeoff expected EKF code
+        gndeffect_state.takeoff_expected = false;
+    } else if (motors->armed() && ap.land_complete) {
+        // if we are armed and haven't yet taken off then we expect an imminent takeoff
         gndeffect_state.takeoff_expected = true;
     }