Remove wxMenuItem::GetBitmapBundle() from wxGTK

This function doesn't exist in the other ports and is not really needed
in this one neither, so just remove it for now.

If we really want to have it, we need to make it available everywhere.

include/wx/gtk/menuitem.h

@@ -33,7 +33,6 @@ public:
     virtual bool IsChecked() const wxOVERRIDE;
     virtual void SetBitmap(const wxBitmapBundle& bitmap);
     virtual wxBitmap GetBitmap() const;
-    const wxBitmapBundle& GetBitmapBundle() const { return m_bitmap; }
     void SetupBitmaps(wxWindow *win);
 
 #if wxUSE_ACCEL

src/gtk/menu.cpp

@@ -1034,7 +1034,7 @@ void wxMenu::GtkAppend(wxMenuItem* mitem, int pos)
             menuItem = gtk_menu_item_new_with_label("");
 #else
             wxGCC_WARNING_SUPPRESS(deprecated-declarations)
-            if (mitem->GetBitmapBundle().IsOk())
+            if (mitem->GetBitmap().IsOk())
             {
                 menuItem = gtk_image_menu_item_new_with_label("");
             }