Known problems fixed in GtkAda 2.4.3

- F106-004 Confusion in Glib.Signal_Id definition on 64 bit systems
  Problem:    The Glib.Signal_Id type is used for both signal id and handler
              id in Gtk.Handlers. In order to fix this confusion, a new
              type and field is used in Gtk.Handlers.Handler_Id.
              This confusion could cause troubles on 64 bit systems only
              where Integer'Size /= Long_Integer'Size
  Workaround: No work around needed. When upgrading to GtkAda 2.4.3, some
              code changes might be needed (Handler.Signal -> Handler.Id,
              Null_Signal_Id -> Null_Handler_Id)

