Update src/libcore/num/mod.rs
Update src/libcore/num/mod.rs

Co-Authored-By: ubsan <5c674ff0ed82ee7268a92fbb9de01a65c6adcd50@gmail.com>
graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust