BUG=libyuv:832
TESTED=out/Release/libyuv_unittest --gtest_filter=*ToNV12* --libyuv_width=1280 --libyuv_height=720 --libyuv_repeat=1000 --libyuv_flags=-1 --libyuv_cpu_info=-1

R=rrwinterton@gmail.com

Change-Id: Id03b4613211fb6a6e163d10daa7c692fe31e36d8
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/1560080
Commit-Queue: Frank Barchard <fbarchard@chromium.org>
Reviewed-by: richard winterton <rrwinterton@gmail.com>
Reviewed-by: Frank Barchard <fbarchard@chromium.org>