automated changes: many (pure) virtual specifiers added

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56276 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/glcanvas.h

@@ -264,6 +264,6 @@ public:
         so that the output of the previous OpenGL commands is displayed on the window.
         Returns @false if an error occurred.
     */
-    bool SwapBuffers();
+    virtual bool SwapBuffers();
 };