determine one extra digit, chop it off

I'm at the point with this now that I'm probably way too deep.  I think
what we have now is probably fine, except that the numbers are sometimes
misleading because they're truncated.

This is the same idea as before, but with the truncation moved one digit
further down.  That way we're kind of still looking at the same number
of digits we think we need to properly represent the number (round
trip).

Change-Id: Iee841607284b4d9f8e848937377ee04a23bf4edb
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/259829
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
66 files changed