Use system's cpu_features library

Remove the copied cpu_featrues.c/h
Use the NDK's cpu_features.a or the one build from android source.
This issue blocked libvpx roll.

BUG=334447
R=andrew@webrtc.org, fischman@webrtc.org, henrike@webrtc.org, wjia@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/8019004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5492 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/system_wrappers/source/cpu_features_android.c

@@ -8,11 +8,7 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#if defined(WEBRTC_CHROMIUM_BUILD)
 #include <cpu-features.h>
-#else
-#include "webrtc/system_wrappers/source/android/cpu-features.h"
-#endif  //  defined(WEBRTC_CHROMIUM_BUILD)
 
 uint64_t WebRtc_GetCPUFeaturesARM(void) {
   return android_getCpuFeatures();