[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_community.c b/bgpd/bgp_community.c
index 64c6810..839927c 100644
--- a/bgpd/bgp_community.c
+++ b/bgpd/bgp_community.c
@@ -617,7 +617,7 @@
 
 /* Return communities hash entry count.  */
 unsigned long
-community_count ()
+community_count (void)
 {
   return comhash->count;
 }