Make singleton SkColorSpaces thread safe

SkColorSpaces may be once-ptrs, so we can reuse common color spaces.
This means that they must be thread safe.  SkMatrix44 is not
thread safe because it maintains a mutable type mask.

This CL ensures that we precompute the type mask so we
can use const SkMatrix44's safely.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2277463002

Review-Url: https://codereview.chromium.org/2277463002
2 files changed