Use Apple's linear transformation equation for XR color types in SkRasterPipeline

Removes an unnecessary form of round() that took a scale parameter,
and adjusts to_unorm() to support extended range inputs that have
valid negative values before being scale/biased into the unorm range.

Adjusts the store operations to use the integer-based linear
transformation equation, which is what the decoding functions already
used. This keeps SkRasterPipeline in sync with the now updated
skcms after https://skia-review.googlesource.com/c/skcms/+/941659 and
https://skia-review.googlesource.com/c/skcms/+/941122

Bug: b/391972897
Change-Id: Idba87643ceeb9a570774b1f0ed68028b88be0e56
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/942776
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
1 file changed