Moved interface list flush to device protocol cleanup hook.

The interface list must be flushed when device protocol is stopped. This
was done in a hardcoded specific hook inside generic protocol routines.
The cleanup hook was originally used for table reference counting late
cleanup, yet it can be also simply used for prettier interface list flush.

sysdep/unix/krt.c

@@ -163,6 +163,15 @@ kif_shutdown(struct proto *P)
   return PS_DOWN;
 }
 
+static void
+kif_cleanup(struct proto *p)
+{
+  if (p->debug & D_EVENTS)
+    log(L_TRACE "%s: Flushing interfaces", p->name);
+  if_start_update();
+  if_end_update();
+}
+
 static int
 kif_reconfigure(struct proto *p, struct proto_config *new)
 {
@@ -239,6 +248,7 @@ struct protocol proto_unix_iface = {
   .init =		kif_init,
   .start =		kif_start,
   .shutdown =		kif_shutdown,
+  .cleanup =		kif_cleanup,
   .reconfigure =	kif_reconfigure,
   .copy_config =	kif_copy_config
 };