Use idle time menu updating when using global menu bar in wxGTK.

We don't get wxEVT_MENU_OPEN events when using the global menu bar so don't
rely on them for updating the menu items status and fall back to idle time
menu updating if the global menu bar is used.

This required changing wxUSE_IDLEMENUUPDATES tests from compile- to run-time
ones.

Closes #14302.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73009 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/frame.h

@@ -205,6 +205,10 @@ protected:
     // frame
     virtual void AttachMenuBar(wxMenuBar *menubar);
 
+    // Return true if we should update the menu item state from idle event
+    // handler or false if we should delay it until the menu is opened.
+    static bool ShouldUpdateMenuFromIdle();
+
     wxMenuBar *m_frameMenuBar;
 #endif // wxUSE_MENUS