-Werror,-Wnon-virtual-dtor

Change-Id: Ibeed52359852451b800e083ddc4c221dea41a294

canvas/source/directx/dx_sprite.hxx

@@ -37,6 +37,9 @@ namespace dxcanvas
             restoreTextures() call failed.
          */
         virtual void redraw() const = 0;
+
+    protected:
+        ~Sprite() {}
     };
 }