use wxOVERRIDE

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76220 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/keyboard/keyboard.cpp

@@ -114,7 +114,7 @@ class MyApp : public wxApp
 {
 public:
     // 'Main program' equivalent: the program execution "starts" here
-    virtual bool OnInit()
+    virtual bool OnInit() wxOVERRIDE
     {
         // create the main application window
         new MyFrame("Keyboard wxWidgets App");