[libcxx-commits] [libcxx] [llvm] [libc++][atomic_ref] Use __atomic_fetch_{add, sub} builtins on floating-points whenever possible (PR #135685)

[Damien L-G via libcxx-commits]

https://github.com/dalg24 ready_for_review https://github.com/llvm/llvm-project/pull/135685