Enable C11 and warnings-as-errors in skcms' Bazel build.

This mirrors the configuration in ninja/common and ninja/clang:
https://skia.googlesource.com/skcms/+/refs/heads/main/ninja/clang
https://skia.googlesource.com/skcms/+/refs/heads/main/ninja/common

Change-Id: Ib7c3d4d5cb15e548876c82777207ab6faa5ace4b
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/771417
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>