gnu: rust-crypto: Move to (gnu packages crates-crypto).
* gnu/packages/crates-io.scm (rust-crypto-secretbox-0.1,
rust-crypto-bigint-0.5, rust-crypto-bigint-0.4, rust-crypto-bigint-0.3,
rust-crypto-bigint-0.2, rust-crypto-common-0.1, rust-crypto-mac-0.11,
rust-crypto-mac-0.10, rust-crypto-mac-0.8, rust-crypto-mac-0.7,
rust-crypto-mac-0.5, rust-crypto-mac-0.4, rust-crypto-tests-0.5,
rust-crypto-hash-0.3): Move from here ...
* gnu/packages/crates-crypto.scm: ... to here.
Change-Id: Ice6d8f1b35afe75f1b0219dc1288ddd4ac8ab4a8