Add setting to increase cost/distance of aircraft linkgraph links

src/vehicle.cpp

@@ -3148,8 +3148,10 @@ static void VehicleIncreaseStats(const Vehicle *front)
 			 * among the wagons in that case.
 			 * As usage is not such an important figure anyway we just
 			 * ignore the additional cargo then.*/
+			EdgeUpdateMode restricted_mode = EUM_INCREASE;
+			if (v->type == VEH_AIRCRAFT) restricted_mode |= EUM_AIRCRAFT;
 			IncreaseStats(Station::Get(last_loading_station), v->cargo_type, front->last_station_visited, v->refit_cap,
-				std::min<uint>(v->refit_cap, v->cargo.StoredCount()), EUM_INCREASE);
+				std::min<uint>(v->refit_cap, v->cargo.StoredCount()), restricted_mode);
 		}
 	}
 }