Update libraries/ to the new libtock.

libraries/crypto/src/lib.rs

@@ -21,7 +21,6 @@ extern crate subtle;
 #[macro_use]
 extern crate arrayref;
 extern crate byteorder;
-extern crate libtock;
 #[macro_use]
 extern crate cbor;
 

libraries/crypto/src/rng256.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use libtock::rng;
+use libtock_drivers::rng;
 
 // Lightweight RNG trait to generate uniformly distributed 256 bits.
 pub trait Rng256 {