buildbreaker2021

Failures in `rules_cc` should be fixed by https://github.com/bazelbuild/rules_cc/commit/b039a551a7b41b70e426e4a3cd60346c89db9b6c I will take a look at `system_library_test` next.

Hey Keith, Thanks for bringing this up. Considering that Java implementation of CcBinary is deleted this might be a bit tough, but have you checked if for Java version of...

Did you mean: `defines = {'KKKEEEYY' : 'VALUE'}`? `:` instead of `,`

This is interesting, I assume it is not just `defines` attribute for cc_library that is affected but all `string_list` attributes on Starlark rules might have similar problem, will investigate further.

Right now the problem is that we don't have a mechanism to expand those in Starlark. Current implementation calls into [expand_location](https://github.com/bazelbuild/bazel/blob/60c9cf3643148b6dce4a6549363f71656dde760c/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl#L766) which works for [source/output path variables](https://bazel.build/reference/be/make-variables#predefined_label_variables).

Hey, is this ready for a review?