(isc_shutdown): Handle struct isc_scb_internal.

src/libraries/libisc-new/src/isc_master.c

@@ -95,7 +95,7 @@ void
 isc_shutdown(struct isc_mcb  * mcb)
 {
   while (mcb->sessions)
-    isc_destroy(mcb, mcb->sessions->scb);
+    isc_destroy(mcb, &mcb->sessions->scb->pub);
 
   isc_free(mcb->scfg);
   isc_free(mcb);