This fixes reproducibility in rust crates from the package phase, again,
see <https://issues.guix.gnu.org/50015>.
Reported by: Christopher Baines (in person).
* guix/build/cargo-build-system.scm (package): When repacking the crate
tarball use standard reproducibility flags.
Change-Id: Ifb1440a023226bf0718e99ce9f95ef981e510cbc