To compile Freeradius 0.8.1 in the NetBSD it has that to modify the 
archive: ~/freeradius-0.8.1/src/main/raduse.c
as in the example below:

raduse.c (original): 

#include <string.h>
#include "sysutmp.h"
#include "conf.h"
#include "radpaths.h"
#include "libradius.h"

#ifndef _AIX

raduse.c (modified):

#include <string.h>
#include "conf.h"
#include "radpaths.h"
#include "libradius.h"
#include "sysutmp.h"

#ifndef _AIX

I wait to have helped other people who are or will have this exactly 
problem. 

-- 
Daniel Dias Gonçalves
f22@netbsd.com.br