[cleanup] functions taking no args should be declared with void args

Use Ansi-C prototypes rather than old K&R method of declaring
function without arguments
diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index 5839d3f..edacd5d 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -274,7 +274,7 @@
 }
 
 static void
-transit_init ()
+transit_init (void)
 {
   transit_hash = hash_create (transit_hash_key_make, transit_hash_cmp);
 }