[libcxx-commits] [libcxx] [libc++][test] `ADDITIONAL_COMPILE_FLAGS` should be a comma-separated list (PR #73541)

[Louis Dionne via libcxx-commits]

ldionne wrote:

As a matter of process, I'd rather we fix all of the occurrences in this PR. We have CI in place that makes this easy, and maintainers can even push to this PR directly.

I also concur with Nikolas here, I think we should make it space-delimited instead.

https://github.com/llvm/llvm-project/pull/73541