Fix MakeCurrent and shader issues with AMD 22.7 driver

src/core/frontend/emu_window.h

@@ -111,6 +111,16 @@ public:
         return nullptr;
     }
 
+    /**
+     * Save current GraphicsContext.
+     */
+    virtual void SaveContext() {};
+
+    /**
+     * Restore saved GraphicsContext.
+     */
+    virtual void RestoreContext() {};
+
     /**
      * Signal that a touch pressed event has occurred (e.g. mouse click pressed)
      * @param framebuffer_x Framebuffer x-coordinate that was pressed