[libcxx-commits] [libcxx] [libc++][math] Generalize workaround for UCRT to `signbit` (PR #212398)

[A. Jiang via libcxx-commits]

frederick-vs-ja wrote:

> I'm really not a big fan. This adds an incredible amount of additional code (as-in doubling the amount of code per math function we have to maintain) for supporting a single libc, which will inevitably have to implement this anyways.

Hmm, do we want to leave the workaround for MS UCRT half baked? I think I can live with removal of workarounds (which will also effectively revert #149234).

https://github.com/llvm/llvm-project/pull/212398