[bgpd] Fix triggerable crash when compiled with --disable-bgp-announce

[bgpd] Fix triggerable crash when compiled with --disable-bgp-announce

2008-07-22 Paul Jakma <paul.jakma@sun.com>

	* HACKING: Document preference for compiler conditional code, over
	  cpp conditional.
	* configure.ac: DISABLE_BGP_ANNOUNCE always should be defined.
	* bgp_{packet,route,advertise}.c: change to compiler testing of
	  DISABLE_BGP_ANNOUNCE, rather than cpp.

2008-07-22 MIYAJIMA Mitsuharu <miyajima.mitsuharu@anchor.jp>

	* bgp_packet.c: (bgp_update_packet_eor) Fix crash triggerable
	  if a bgpd was compiled with --disable-bgp-announce and if GR is
	  advertised by peer.