Fix the position calculating of insert a radio menu item

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77795 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/univ/menuitem.h

@@ -52,6 +52,8 @@ public:
     void SetAsRadioGroupStart();
     void SetRadioGroupStart(int start);
     void SetRadioGroupEnd(int end);
+    int GetRadioGroupStart();
+    int GetRadioGroupEnd();
 
     // wxUniv-specific methods for implementation only starting from here