Update from https://crrev.com/312398

tools/clang/translation_unit/test_files/test.cc

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "test.h"
 
+#include <bits/wchar.h>
+
 #include "binomial.h"
 
 // Notice that "binomial.h" is included both here and in the "test.h" file.
 // The tool should however print the path to this header file only once.
 
 int main() {
   // Just some nonesense calculations.
   int result = calculateNumberOfWaysToDistributeNItemsAmongKPersons(10, 5);
   return result + binomial(42, 1);
 }