Add initial prototype for the GN meta-buildsystem.

tools/gn/config_values.cc

Index: tools/gn/config_values.cc
diff --git a/native_client_sdk/src/libraries/nacl_io_test/mount_mock.cc b/tools/gn/config_values.cc
similarity index 62%
copy from native_client_sdk/src/libraries/nacl_io_test/mount_mock.cc
copy to tools/gn/config_values.cc
index 1006822ed21767e07ef0032ddefddca842698d98..53466dfd79180b8c211b9d9202a1db73b9166f36 100644
--- a/native_client_sdk/src/libraries/nacl_io_test/mount_mock.cc
+++ b/tools/gn/config_values.cc
@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "mount_mock.h"
+#include "tools/gn/config_values.h"
 
-MountMock::MountMock() {}
-
-MountMock::~MountMock() {}
+ConfigValues::ConfigValues() {
+}
 
+ConfigValues::~ConfigValues() {
+}