misc/cgo/testso: do not leave out file behind

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/5461044

misc/cgo/testso/test.bash

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Copyright 2011 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.
+
+set -e
+gomake out
+LD_LIBRARY_PATH=. ./out
+gomake clean

src/run.bash

@@ -78,8 +78,7 @@ gotest
 [ "$GOHOSTOS" == darwin ] ||
 (xcd ../misc/cgo/testso
 gomake clean
-gomake out
-LD_LIBRARY_PATH=. ./out
+./test.bash
 ) || exit $?
 
 (xcd ../doc/progs