See:
http://lists.ibiblio.org/pipermail/sm-commit/2006-August/005535.html

--- ./whois.c.orig	2007-08-09 02:17:28.000000000 +0200
+++ ./whois.c	2007-08-09 02:17:38.000000000 +0200
@@ -6,7 +6,7 @@
  */
 
 /* for AI_IDN */
-#define _GNU_SOURCE
+//#define _GNU_SOURCE
 
 /* System library */
 #include <stdio.h>