Reintroduce `extern crate` for non-Cargo dependencies, in tests.
Reintroduce `extern crate` for non-Cargo dependencies, in tests.

graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust