AVX2 optimized 10 bit YUV to ARGB.

Bug: libyuv:751
Test: H010ToARGB unittest
Change-Id: I705630beb62714b52042c2a5dcdb8b7859e734ae
Reviewed-on: https://chromium-review.googlesource.com/852563
Commit-Queue: Frank Barchard <fbarchard@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Reviewed-by: richard winterton <rrwinterton@gmail.com>