AP_Proximity: add override keyword where required

libraries/AP_Proximity/AP_Proximity_LightWareSF40C.h

@@ -16,11 +16,11 @@ public:
     static bool detect(AP_SerialManager &serial_manager);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const;
-    float distance_min() const;
+    float distance_max() const override;
+    float distance_min() const override;
 
 private:
 

libraries/AP_Proximity/AP_Proximity_MAV.h

@@ -11,14 +11,14 @@ public:
     AP_Proximity_MAV(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const { return _distance_max; }
-    float distance_min() const { return _distance_min; };
+    float distance_max() const override { return _distance_max; }
+    float distance_min() const override { return _distance_min; };
 
     // get distance upwards in meters. returns true on success
-    bool get_upward_distance(float &distance) const;
+    bool get_upward_distance(float &distance) const override;
 
     // handle mavlink DISTANCE_SENSOR messages
     void handle_msg(mavlink_message_t *msg) override;

libraries/AP_Proximity/AP_Proximity_RPLidarA2.h

@@ -45,11 +45,11 @@ public:
     static bool detect(AP_SerialManager &serial_manager);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const;
-    float distance_min() const;
+    float distance_max() const override;
+    float distance_min() const override;
 
 private:
     enum rp_state {

libraries/AP_Proximity/AP_Proximity_RangeFinder.h

@@ -13,14 +13,14 @@ public:
     AP_Proximity_RangeFinder(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const { return _distance_max; }
-    float distance_min() const { return _distance_min; }
+    float distance_max() const override { return _distance_max; }
+    float distance_min() const override { return _distance_min; }
 
     // get distance upwards in meters. returns true on success
-    bool get_upward_distance(float &distance) const;
+    bool get_upward_distance(float &distance) const override;
 
 private:
 

libraries/AP_Proximity/AP_Proximity_SITL.h

@@ -17,11 +17,11 @@ public:
     void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const;
-    float distance_min() const;
+    float distance_max() const override;
+    float distance_min() const override;
 
     // get distance upwards in meters. returns true on success
-    bool get_upward_distance(float &distance) const;
+    bool get_upward_distance(float &distance) const override;
 
 private:
     SITL::SITL *sitl;

libraries/AP_Proximity/AP_Proximity_TeraRangerTower.h

@@ -16,11 +16,11 @@ public:
     static bool detect(AP_SerialManager &serial_manager);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const;
-    float distance_min() const;
+    float distance_max() const override;
+    float distance_min() const override;
 
 private:
 

libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.h

@@ -15,11 +15,11 @@ public:
     static bool detect(AP_SerialManager &serial_manager);
 
     // update state
-    void update(void);
+    void update(void) override;
 
     // get maximum and minimum distances (in meters) of sensor
-    float distance_max() const;
-    float distance_min() const; 
+    float distance_max() const override;
+    float distance_min() const override;
 
 private: