Remove the mentions of the native OSX wxListCtrl control

This control was removed during the Carbon code removal in commit
5ba67c67e4, so the system option
does nothing now (and was only mentioned in the documentation
and the sample).

samples/listctrl/listtest.h

@@ -148,9 +148,6 @@ protected:
     void OnToggleLines(wxCommandEvent& event);
     void OnToggleHeader(wxCommandEvent& event);
     void OnToggleBell(wxCommandEvent& event);
-#ifdef __WXOSX__
-    void OnToggleMacUseGeneric(wxCommandEvent& event);
-#endif // __WXOSX__
     void OnFind(wxCommandEvent& event);
     void OnToggleItemCheckBox(wxCommandEvent& event);
     void OnGetItemCheckBox(wxCommandEvent& event);
@@ -245,9 +242,6 @@ enum
     LIST_FREEZE,
     LIST_THAW,
     LIST_TOGGLE_LINES,
-#ifdef __WXOSX__
-    LIST_MAC_USE_GENERIC,
-#endif
     LIST_CHECKVISIBILITY,
     LIST_CTRL                   = 1000
 };