new color util to compute constants needed based on white point.
[ RUN ] LibYUVColorTest.TestFullYUVV
hist -2 -1 0 1 2
red 0 1627136 13670144 1479936 0
green 319285 3456836 9243059 3440771 317265
blue 0 1561088 14202112 1014016 0
Bug: libyuv:877, b/178283356
Change-Id: If432ebfab76b01302fdb416a153c4f26ca0832d6
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/2678859
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
Reviewed-by: richard winterton <rrwinterton@gmail.com>