http://berklix.com/~jhs/src/bsd/fixes/FreeBSD/ports/gen/security/nmap/

This patch made against current on 2009 11 10,
although I observed the need on 6.4-RELEASE

# *** 6.4-RELEASE/ports/security/nmap/Makefile	Fri Jul 17 07:53:16 2009
# --- new-generic/ports/security/nmap/Makefile	Tue Nov 10 16:44:23 2009
# ***************
# *** 18,23 ****
# --- 18,24 ----
#   COMMENT=	Port scanning utility for large networks
#   
#   LIB_DEPENDS=	pcre.0:${PORTSDIR}/devel/pcre
# + BUILD_DEPENDS=	autoconf:${PORTSDIR}/devel/autoconf213
#   
#   USE_LUA=	5.1
#   LUA_COMPS=	lua

*** 6.4-RELEASE/ports/security/nmap/Makefile	Sun Sep  7 12:20:16 2008
--- new-generic/ports/security/nmap/Makefile	Thu Sep  1 02:38:19 2011
***************
*** 19,24 ****
--- 19,26 ----
  LIB_DEPENDS=	pcre.0:${PORTSDIR}/devel/pcre \
  		dnet.1:${PORTSDIR}/net/libdnet
  
+ BUILD_DEPENDS=	autoconf:${PORTSDIR}/devel/autoconf213
+ 
  USE_LUA=	5.1
  LUA_COMPS=	lua
  USE_BZIP2=	yes