some app.h cleanup: minimize includes, use static cast

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41099 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/stackwalk.h

@@ -12,6 +12,8 @@
 #ifndef _WX_MSW_STACKWALK_H_
 #define _WX_MSW_STACKWALK_H_
 
+#include "wx/arrstr.h"
+
 // these structs are declared in windows headers
 struct _CONTEXT;
 struct _EXCEPTION_POINTERS;