This functionality has been replaced by the new sleep library
which supports more then just DBUS systems.
* lisp/obsolete/gnus-dbus.el: Add Obsolete-since header. Add
commentary.
(gnus-dbus-close-on-sleep, gnus-dbus-sleep-registration-object)
(gnus-dbus-register-sleep-signal gnus-dbus-sleep-handler)
(gnus-dbus-unregister-sleep-signal): Mark as obsolete.