$NetBSD$

Fix build with gcc4.

--- runtime/interp.c~	1997-06-27 09:59:03.000000000 -0400
+++ runtime/interp.c	2008-09-04 20:53:27.000000000 -0400
@@ -177,10 +177,10 @@ value interprete(prog)
   register value * asp;
   register value * rsp;
 #else
-  register code_t pc;
-  register value accu;
-  register value * asp;
-  register value * rsp;
+  register volatile code_t pc;
+  register volatile value accu;
+  register value * volatile asp;
+  register value * volatile rsp;
 #endif
 #endif
 #endif
