Don't fail to unregister the stale timeout during shutdown.

src/libraries/libisc-new/ChangeLog

 2003-08-01  Per Cederqvist  <ceder@ceder.dyndns.org>
 
+	Don't fail to unregister the stale timeout during shutdown.
+	* src/isc_session.c (isc_set_read_callback): Call
+	isc_cancel_stale_output_callback().  Removed redundant checks.
+	(isc_destroy): Call isc_cancel_stale_output_callback().
+
 	Call a callback function if a client becomes stale.
 	* src/isc.h (isc_stale_output_cb): New typedef.
 	(isc_cfg_stale_timeout): New function.