sigpause(3) is only declared if _GNU_SOURCE is defined.

--- a/hunt/hunt/otto.c
+++ b/hunt/hunt/otto.c
@@ -43,6 +43,8 @@
  *	Id: otto.c,v 1.14 2003/04/16 06:11:54 gregc Exp
  */
 
+#define _GNU_SOURCE /* for sigpause(3) */
+
 #include <sys/cdefs.h>
 #ifndef lint
 __RCSID("$NetBSD: otto.c,v 1.8 2004/11/05 21:30:32 dsl Exp $");