added a define G_HOOK_DEFERRED_DESTROY, to substitute a noop

added a define G_HOOK_DEFERRED_DESTROY, to substitute a noop

Sun Jan 17 14:13:52 1999  Tim Janik  <timj@gtk.org>

        * glib.h: added a define G_HOOK_DEFERRED_DESTROY, to substitute a noop
        GHookList.hook_destroy function.

        * ghook.c (g_hook_destroy_link): don't really call hook_destroy if it
        is G_HOOK_DEFERRED_DESTROY. for the case where we invoke hook->destroy()
        we now clean up the hook completely afterwards, i.e. data, func and
        destroy are immediately set to NULL and hook_free can't play with that
        values anymore.

        * gmain.c (g_source_add): set hook_destroy to G_HOOK_DEFERRED_DESTROY,
        instead of using an ugly _noop() hack, this is to avoid an uneccessary
        function invokation. set hook_free to g_source_destroy_func, this way
        we always invoke the destroy notifiers for user_data and source_data
        after execution of dispatch(). thus, g_source_destroy_func() will always
        be called within the main_loop lock (this wasn't really assured
        before), and can release and reaquire the look around destroy notifier
        invokation.