[libcxx-commits] [libcxx] [libc++][C++03] Fix modules (PR #165706)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne commented:

Per live discussion, let's make the frozen C++03 headers be a config-site decision that we decide at configure time.

This implies making `__config` includable from public headers directly and then making the decision of whether to use the frozen headers or not. `__config` would include `__config_site` and then forward to either the frozen config or not.

https://github.com/llvm/llvm-project/pull/165706