Expire lost items at the update instead of continuously

Replace thread DeleteItems running delete_lostitems() by simple
function delete_old_lostitems(), and call it from update_main().

src/lib/update/main.c

@@ -173,6 +173,7 @@ update_main(void)
     unit_cargo_init();
     delete_old_announcements();
     delete_old_news();
+    delete_old_lostitems();
     /* Clear all the telegram flags */
     for (cn = 0; cn < MAXNOC; cn++)
 	clear_telegram_is_new(cn);