Use cpu_features library provided by android_tools/ndk.

Since multiple projects are using cpu-features library on Android, android_tools/ndk has provided a static library cpu_features. All users will link against this library to avoid function re-definition.

BUG=161417
Review URL: https://codereview.chromium.org/11308086

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@168564 0039d316-1c4b-4281-b951-d872f2087c98

third_party/libwebp/README.chromium

@@ -20,7 +20,6 @@ Local changes:
  * Removed examples/, documentation and build related files, keeping only
    the contents of src/ less mux/ which is unused.
  * Merged COPYING/PATENTS to LICENSE
- * Added cpu-features.[hc] from the Android NDK to dsp/.
  * Revert VP8 encoder changes to avoid WebKit layout test conflicts
    (fast/canvas/canvas-toDataURL)
    WebKit bug tracking test update: