reflect the presence of signal connections through unsetting

reflect the presence of signal connections through unsetting

Sat May  9 00:03:12 1998  Tim Janik  <timj@gtk.org>

        * gtk/gtksignal.c (gtk_signal_handler_unref): reflect the presence of
        signal connections through unsetting GTK_CONNECTED.
        (gtk_signal_handler_insert): reflect the presence of signal connections
        through setting GTK_CONNECTED.
        (gtk_signal_real_emit): only check for handler emissions if the object
        has the GTK_CONNECTED flag set.
        (gtk_signal_handler_pending): don't check for pending handlers if the
        GTK_CONNECTED flag is not set for this object.

        * gtk/gtkobject.h (enum): new flag GTK_CONNECTED to indicate whether
        a GtkObject has signal handler connections.

        * gtk/gtkobject.c (gtk_object_real_destroy): only if GTK_CONNECTED is
        set for this object call gtk_signal_handlers_destroy().

        * gtk/gtktypeutils.h (GTK_TYPE_IS_A): deprecated macro, since it caused
        multiple processing of macro args.

        * gtk/gtktypeutils.c:
        * gtk/gtkobject.c:
        * gtk/gtkwidget.c:
        * gtk/gtksignal.c: reverted GTK_TYPE_IS_A back to gtk_type_is_a.