Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/test/RTPjitter.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
 //TODO(hlundin): Reformat file to meet style guide.
 
 /* header includes */
 #include <float.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #ifdef WIN32
 #include <winsock2.h>
 #include <io.h>
 #endif
 #ifdef WEBRTC_LINUX
 #include <netinet/in.h>
 #endif
 
 #include <assert.h>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/typedefs.h"
 
 /*********************/
 /* Misc. definitions */
 /*********************/
 
 #define FIRSTLINELEN 40
 #define CHECK_NOT_NULL(a) if((a)==NULL){ \
     fprintf(stderr,"\n %s \n line: %d \nerror at %s\n",__FILE__,__LINE__,#a ); \
     return(-1);}
@@ skipping 181 matching lines @@
 
 int compare_arr_time(const void *xp, const void *yp) {
 
   if(((arr_time *)xp)->time == ((arr_time *)yp)->time)
     return(0);
   else if(((arr_time *)xp)->time > ((arr_time *)yp)->time)
     return(1);
 
   return(-1);
 }