misc: Remove unnecessary "extern crate"

Now all crates use edition = "2018" then the majority of the "extern
crate" statements can be removed. Only those for importing macros need
to remain.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vhost_user_net/src/lib.rs

@@ -6,11 +6,6 @@
 //
 // SPDX-License-Identifier: (Apache-2.0 AND BSD-3-Clause)
 
-extern crate log;
-extern crate net_util;
-extern crate vhost;
-extern crate vhost_user_backend;
-
 use libc::{self, EFD_NONBLOCK};
 use log::*;
 use net_util::{

vhost_user_net/src/main.rs

@@ -8,7 +8,6 @@
 
 #[macro_use(crate_version, crate_authors)]
 extern crate clap;
-extern crate vhost_user_net;
 
 use clap::{App, Arg};
 use vhost_user_net::start_net_backend;