gnu: rust-rand-hc-0.1: Don't hide package.

* gnu/packages/crates-io.scm (rust-rand-hc-0.1):[arguments] Skip build.
Add urst-rand-core-0.3 to cargo-inputs.
[properties] Remove field.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>