androidtest.bash: missing !

LGTM=iant
R=bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/112010045

src/androidtest.bash

-#/usr/bin/env bash
+#!/usr/bin/env bash
 # Copyright 2014 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.