gc: bug302

Fixed by http://code.google.com/p/go/source/detail?r=d1f41e20a90e
This just adds a test and checks the return value of Bprint.

R=ken2
CC=golang-dev
https://golang.org/cl/1949042

src/cmd/gc/export.c

@@ -176,7 +176,8 @@ dumpexporttype(Sym *s)
 		yyerror("export of incomplete type %T", t);
 		return;
 	}
-	Bprint(bout, "type %#T %l#T\n",  t, t);
+	if(Bprint(bout, "type %#T %l#T\n",  t, t) < 0)
+		fatal("Bprint failed for %T", t);
 }
 
 static int

test/fixedbugs/bug302.dir/main.go

+// Copyright 2010 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.
+
+package main
+
+import _ "./p"

test/fixedbugs/bug302.go

+// $G $D/bug302.dir/p.go && $G $D/bug302.dir/main.go
+
+// Copyright 2010 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.
+