Don't compile in root certs on Android.

runtime/bin/root_certificates_unsupported.cc

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
-#include "vm/timer.h"
-#include "vm/json_stream.h"
 
 namespace dart {
+namespace bin {
 
+const unsigned char* root_certificates_pem = NULL;
+unsigned int root_certificates_pem_length = 0;
 
-
+}  // namespace bin
 }  // namespace dart