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
5 files changed