edition: Remove extern crate lines

In Rust 2018 edition, `extern crate` is no longer required for importing
from other crates. Instead of writing:

    extern crate dep;
    use dep::Thing;

we write:

    use dep::Thing;

In this approach, macros are imported individually from the declaring
crate rather than through #[macro_use]. Before:

    #[macro_use]
    extern crate sys_util;

After:

    use sys_util::{debug, error};

The only place that `extern crate` continues to be required is in
importing the compiler's proc_macro API into a procedural macro crate.
This will hopefully be fixed in a future Rust release.

    extern crate proc_macro;

TEST=cargo check
TEST=cargo check --all-features
TEST=cargo check --target aarch64-unknown-linux-gnu
TEST=local kokoro

Change-Id: I0b43768c0d81f2a250b1959fb97ba35cbac56293
Reviewed-on: https://chromium-review.googlesource.com/1565302
Commit-Ready: David Tolnay <dtolnay@chromium.org>
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: David Tolnay <dtolnay@chromium.org>

3 files changed, 1 insertions, 11 deletions

diff --git a/fuzz/block_fuzzer.rs b/fuzz/block_fuzzer.rs
index 5c3106a..f315a87 100644
--- a/fuzz/block_fuzzer.rs
+++ b/fuzz/block_fuzzer.rs
@@ -3,11 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate devices;
-extern crate libc;
-extern crate sys_util;
-
-use sys_util::{EventFd, GuestAddress, GuestMemory, SharedMemory};
 
 use std::fs::File;
 use std::io::{Cursor, Read, Seek, SeekFrom};
@@ -20,6 +15,7 @@ use std::sync::atomic::AtomicUsize;
 use std::sync::Arc;
 
 use devices::virtio::{Block, Queue, VirtioDevice};
+use sys_util::{EventFd, GuestAddress, GuestMemory, SharedMemory};
 
 const MEM_SIZE: u64 = 256 * 1024 * 1024;
 const DESC_SIZE: u64 = 16; // Bytes in one virtio descriptor.
diff --git a/fuzz/qcow_fuzzer.rs b/fuzz/qcow_fuzzer.rs
index 0f7ff2a..e6175ff 100644
--- a/fuzz/qcow_fuzzer.rs
+++ b/fuzz/qcow_fuzzer.rs
@@ -3,9 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate libc;
-extern crate qcow;
-extern crate sys_util;
 
 use qcow::QcowFile;
 use sys_util::SharedMemory;
diff --git a/fuzz/zimage_fuzzer.rs b/fuzz/zimage_fuzzer.rs
index 13b67b3..fdcb7db 100644
--- a/fuzz/zimage_fuzzer.rs
+++ b/fuzz/zimage_fuzzer.rs
@@ -3,9 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate kernel_loader;
-extern crate libc;
-extern crate sys_util;
 
 use sys_util::{GuestAddress, GuestMemory};