zero.rs (or something like it) is still required, because there's certain lang items that are required/useful (e.g. #[start], destructors, failure, vector bound

zero.rs (or something like it) is still required, because there's certain lang items that are required/useful (e.g. #[start], destructors, failure, vector bounds checks). (e.g. https://github.com/huonw/rust-malloc/blob/master/zero.rs https://github.com/huonw/rust-malloc/blob/master/zero.rs)