AP_Notify: add override to display methods

libraries/AP_Notify/Display_SH1106_I2C.h

@@ -13,11 +13,11 @@ public:
     static bool hw_autodetect() { return true; }
 
 protected:
-    virtual bool hw_init();
-    virtual bool hw_update();
-    virtual bool set_pixel(uint16_t x, uint16_t y);
-    virtual bool clear_pixel(uint16_t x, uint16_t y);
-    virtual bool clear_screen();
+    bool hw_init() override;
+    bool hw_update() override;
+    bool set_pixel(uint16_t x, uint16_t y) override;
+    bool clear_pixel(uint16_t x, uint16_t y) override;
+    bool clear_screen() override;
 
     void _update_timer() override;
 

libraries/AP_Notify/Display_SSD1306_I2C.h

@@ -11,11 +11,11 @@
 class Display_SSD1306_I2C: public Display_OLED_I2C {
 
 protected:
-    virtual bool hw_init();
-    virtual bool hw_update();
-    virtual bool set_pixel(uint16_t x, uint16_t y);
-    virtual bool clear_pixel(uint16_t x, uint16_t y);
-    virtual bool clear_screen();
+    bool hw_init() override;
+    bool hw_update() override;
+    bool set_pixel(uint16_t x, uint16_t y) override;
+    bool clear_pixel(uint16_t x, uint16_t y) override;
+    bool clear_screen() override;
 
     void _update_timer() override;