gc: fix compiler crash

R=ken2
CC=dho
https://golang.org/cl/179097

src/cmd/gc/walk.c

@@ -231,6 +231,8 @@ walkdef(Node *n)
 		t->printed = 0;
 		t->method = nil;
 		t->nod = N;
+		t->printed = 0;
+		t->deferwidth = 0;
 
 		// double-check use of type as map key
 		// TODO(rsc): also use of type as receiver?

test/fixedbugs/bug235.go

+// $G $D/$F.go
+
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// used to crash the compiler
+
+package main
+
+type T struct {
+	x [4]byte
+}
+
+var p *T
+var v = *p
+