$NetBSD: patch-ad,v 1.1 2008/09/05 02:07:51 dholland Exp $

Fix 64-bit build.

--- runtime/signals.c~	1995-11-10 10:10:32.000000000 -0500
+++ runtime/signals.c	2008-09-04 21:10:48.000000000 -0400
@@ -5,6 +5,8 @@
 #include "signals.h"
 #include "stacks.h"
 
+value callback(value closure, value argument);
+
 Volatile int async_signal_mode = 0;
 Volatile code_t pending_signal_handler;
 Volatile int pending_signal = 0;