set us simd
set us simd

R=harryjin@google.com
BUG=libyuv:448

Review URL: https://webrtc-codereview.appspot.com/55629004.

yarrcc/libyuv-ios,lyx2014/yuv,disigma/yuv,yarrcc/libyuv-ios,yarrcc/libyuv-ios,lemenkov/libyuv,lyx2014/yuv,lyx2014/yuv,lyx2014/libyuv_free,lemenkov/libyuv,disigma/yuv,lyx2014/libyuv_free,lemenkov/libyuv,disigma/yuv,lyx2014/libyuv_free,lyx2014/libyuv_free,lyx2014/yuv,lemenkov/libyuv,yarrcc/libyuv-ios