[glibmm] Gio::Menu::insert/prepend/add_item(): Const correction.

[Murray Cumming <murrayc src gnome org>]

commit 45b03a50c45d3305aa9414f9e57aab0543125bb0
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Dec 2 13:01:36 2016 +0100

    Gio::Menu::insert/prepend/add_item(): Const correction.
    
    We can do this now that we can break ABI.

 gio/src/menu.hg |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gio/src/menu.hg b/gio/src/menu.hg
index ad129a9..e3f1d6d 100644
--- a/gio/src/menu.hg
+++ b/gio/src/menu.hg
@@ -48,10 +48,9 @@ public:
 
   _WRAP_METHOD(void freeze(), g_menu_freeze)
 
-  //TODO: Make the item "const Glib::RefPtr<const MenuItem>&" when we can break ABI? The function is 
documented as just copying its attributes.
-  _WRAP_METHOD(void insert_item(int position, const Glib::RefPtr<MenuItem>& item), g_menu_insert_item)
-  _WRAP_METHOD(void prepend_item(const Glib::RefPtr<MenuItem>& item), g_menu_prepend_item)
-  _WRAP_METHOD(void append_item(const Glib::RefPtr<MenuItem>& item), g_menu_append_item)
+  _WRAP_METHOD(void insert_item(int position, const Glib::RefPtr<const MenuItem>& item), g_menu_insert_item)
+  _WRAP_METHOD(void prepend_item(const Glib::RefPtr<const MenuItem>& item), g_menu_prepend_item)
+  _WRAP_METHOD(void append_item(const Glib::RefPtr<const MenuItem>& item), g_menu_append_item)
   _WRAP_METHOD(void remove(int position), g_menu_remove)
   _WRAP_METHOD(void remove_all(), g_menu_remove_all)
 
@@ -63,6 +62,7 @@ public:
   _WRAP_METHOD(void prepend(const Glib::ustring& label, const Glib::ustring& detailed_action{?}), 
g_menu_prepend)
   _WRAP_METHOD(void append(const Glib::ustring& label, const Glib::ustring& detailed_action{?}), 
g_menu_append)
 
+// TODO: Should the MenuModel be const too?
   _WRAP_METHOD(void insert_section(int position, const Glib::ustring& label{?}, const 
Glib::RefPtr<MenuModel>& section), g_menu_insert_section)
   _WRAP_METHOD(void prepend_section(const Glib::ustring& label{?}, const Glib::RefPtr<MenuModel>& section), 
g_menu_prepend_section)
   _WRAP_METHOD(void append_section(const Glib::ustring& label{?}, const Glib::RefPtr<MenuModel>& section), 
g_menu_append_section)