I have NO IDEA if these are correct. Implementation was 'inspired by' https://github.com/rust-lang-deprecated/time/commit/4ca23fb14ddf44fd90609fec6a2fb1efcedb8ea3. Pretty darn certain that negative values won't work

This stops configure scripts from identifying them as valid

This undos a workaround. Jeremy moved the ralloc stuff to platform and suddenly this seems to work again. I don't know what is different from when I tried this before and now, but I don't really care