Official Skia documentation suggests that it's [_highly
recommended_](https://skia.org/docs/user/build/#highly-recommended-build-with-clang-cl)
to build Skia with Clang-CL on Windows, and that this dramatically
improves Skia performance with Software rendering and in other areas.
This corresponds with my experience, so here it is.

Related Skia-pack PR: https://github.com/JetBrains/skia-pack/pull/64

Prerequisite: #1024