Add style guidance for `k` prefix on constants.

The style guide only mentioned the `k` prefix for enums, but it is
also used throughout Skia for constant values.

Also removed guidance about using anonymous enums to declare an
integral constant. static constexprs should be preferred here.

Change-Id: I2f7d4d375cc914d4efb9fe60fbd90ddaaf8c1b69
No-Try: true
Docs-Preview: https://skia.org/?cl=308919
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/308919
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
1 file changed