[libcxx-commits] [libcxx] [libc++] Remove libc++'s own fenv.h (PR #194629)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne approved this pull request.

Same as https://github.com/llvm/llvm-project/pull/193716, I think this makes sense, but heads up to @llvm/libcxx-vendors @var-const @ian-twilightcoder 

https://github.com/llvm/llvm-project/pull/194629