Remove redundant extern crate declarations

With Rust edition 2018, it is no longer necessary to declare
dependencies in the code using `extern crate`.  Therefore, this patch
removes these declarations and replaces them with `use` declarations if
necessary.

1 files changed, 2 insertions, 4 deletions

diff --git a/src/lib.rs b/src/lib.rs
index aab717b..2df704e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -91,10 +91,6 @@
     unused,
 )]
 
-extern crate libc;
-extern crate nitrokey_sys;
-extern crate rand;
-
 mod auth;
 mod config;
 mod device;
@@ -104,6 +100,8 @@ mod pws;
 mod tests;
 mod util;
 
+use nitrokey_sys;
+
 pub use crate::auth::{Admin, Authenticate, User};
 pub use crate::config::Config;
 pub use crate::device::{connect, Device, DeviceWrapper, Pro, Storage, StorageStatus, VolumeStatus};