lib: address -Wunused-but-set-variable

* if.c
  * if_dump(): 'node', 'c'
* distribute.c
  * distribute_list_all(): 'dist'
  * distribute_list(): 'dist'
  * districute_list_prefix_all(): 'dist'
* if_rmap.c
  * if_rmap(): 'if_rmap'
* vty.c
  * vty_accept(): 'vty'
diff --git a/lib/vty.c b/lib/vty.c
index e403159..4fed271 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -1685,7 +1685,6 @@
 vty_accept (struct thread *thread)
 {
   int vty_sock;
-  struct vty *vty;
   union sockunion su;
   int ret;
   unsigned int on;
@@ -1770,7 +1769,7 @@
   if (bufp)
     XFREE (MTYPE_TMP, bufp);
 
-  vty = vty_create (vty_sock, &su);
+  vty_create (vty_sock, &su);
 
   return 0;
 }