bgpd: code cleanup

* bgpd/bgp_aspath.c
  * ashash: only used in one file, make static
  * aspath_count_numas(): dead code, sayonara
* bgpd/bgpd.c
  * peer_nsf_stop(): only used in one file, make static
* bgpd/bgp_packet.h
  * bgp_capability_receive(): add missing prototype for a
    global function
diff --git a/bgpd/bgp_packet.h b/bgpd/bgp_packet.h
index 85d6407..8f0ebe3 100644
--- a/bgpd/bgp_packet.h
+++ b/bgpd/bgp_packet.h
@@ -52,4 +52,6 @@
 			      afi_t, safi_t, struct peer *);
 extern void bgp_default_withdraw_send (struct peer *, afi_t, safi_t);
 
+extern int bgp_capability_receive (struct peer *, bgp_size_t);
+
 #endif /* _QUAGGA_BGP_PACKET_H */