adding wxFALLTHROUGH where until now we had comments, allows for code-analysis support

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76399 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/listctrl.cpp

@@ -1110,7 +1110,7 @@ void wxListHeaderWindow::OnPaint( wxPaintEvent &WXUNUSED(event) )
         {
             default:
                 wxFAIL_MSG( wxT("unknown list item format") );
-                // fall through
+                wxFALLTHROUGH;
 
             case wxLIST_FORMAT_LEFT:
                 xAligned = x;