[rust png] Use public header of skcms.

Using the private header means that `gn check` in Chromium complains
in https://crrev.com/c/5747366

Bug: chromium:356874896
Change-Id: I228d314f442d1b3ccaa1eac292b38f225696d5cd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/894549
Commit-Queue: Łukasz Anforowicz <lukasza@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Łukasz Anforowicz <lukasza@google.com>
1 file changed