AP_VisualOdom: removed empty constructors

libraries/AP_VisualOdom/AP_VisualOdom_MAV.cpp

@@ -23,12 +23,6 @@
 
 extern const AP_HAL::HAL& hal;
 
-// constructor
-AP_VisualOdom_MAV::AP_VisualOdom_MAV(AP_VisualOdom &frontend) :
-    AP_VisualOdom_Backend(frontend)
-{
-}
-
 // consume vision position estimate data and send to EKF. distances in meters
 void AP_VisualOdom_MAV::handle_vision_position_estimate(uint64_t remote_time_us, uint32_t time_ms, float x, float y, float z, const Quaternion &attitude, float posErr, float angErr, uint8_t reset_counter)
 {

libraries/AP_VisualOdom/AP_VisualOdom_MAV.h

@@ -9,7 +9,7 @@ class AP_VisualOdom_MAV : public AP_VisualOdom_Backend
 
 public:
     // constructor
-    AP_VisualOdom_MAV(AP_VisualOdom &frontend);
+    using AP_VisualOdom_Backend::AP_VisualOdom_Backend;
 
     // consume vision position estimate data and send to EKF. distances in meters
     void handle_vision_position_estimate(uint64_t remote_time_us, uint32_t time_ms, float x, float y, float z, const Quaternion &attitude, float posErr, float angErr, uint8_t reset_counter) override;