Remove workaround for `pub extern crate`
Remove workaround for `pub extern crate`

On semi-recent Rust versions (I think 1.8+) this now works properly.

berkowski/nix,carllerche/nix-rust,geofft/nix-rust,Susurrus/nix,asomers/nix,MarkusJais/nix-rust,Susurrus/nix,Susurrus/nix,MarkusJais/nix-rust,nix-rust/nix,geofft/nix-rust,berkowski/nix,berkowski/nix,xd009642/nix,carllerche/nix-rust,xd009642/nix,asomers/nix,nix-rust/nix,carllerche/nix-rust,geofft/nix-rust,xd009642/nix,MarkusJais/nix-rust