Enable the -Wundef warning for clang

webrtc/modules/desktop_capture/win/cursor_unittest.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <memory>
 
-#include "testing/gmock/include/gmock/gmock.h"
+#include "webrtc/test/gmock.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
 #include "webrtc/modules/desktop_capture/win/cursor.h"
 #include "webrtc/modules/desktop_capture/win/cursor_unittest_resources.h"
 #include "webrtc/modules/desktop_capture/win/scoped_gdi_object.h"
 
 namespace webrtc {
 
 namespace {
@@ skipping 57 matching lines @@
                                             IDD_CURSOR1_32BPP));
 
   EXPECT_TRUE(ConvertToMouseShapeAndCompare(IDD_CURSOR2_1BPP,
                                             IDD_CURSOR2_32BPP));
 
   EXPECT_TRUE(ConvertToMouseShapeAndCompare(IDD_CURSOR3_4BPP,
                                             IDD_CURSOR3_32BPP));
 }
 
 }  // namespace webrtc