safemem is unmaintained

The latest crates.io release was in 2019. The repository has been archived by the author. Migration - safemem::copyoverslice, srcidx, destidx, len; can be replaced with slice.copywithinsrcidx..srcidx+len, destidx; as of rust 1.37.0. - safemem::writebytesslice, byte; can be replaced with...