* gnu/packages/crates-io.scm (rust-rustc-rayon-core-0.4) [cargo-development-inputs]: Add rust-libc-0.2, rust-rand-0.8, rust-rand-xorshift-0.3, rust-scoped-tls-1. Change-Id: I31bce5f456b99e72147c37e1b2c53f3fd1e1572e