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>

vmm/src/api/mod.rs

@@ -28,9 +28,6 @@
 //!    response channel Receiver.
 //! 5. The thread handles the response and forwards potential errors.
 
-extern crate vm_device;
-extern crate vmm_sys_util;
-
 pub use self::http::start_http_fd_thread;
 pub use self::http::start_http_path_thread;
 

vmm/src/lib.rs

@@ -3,21 +3,14 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-extern crate anyhow;
-extern crate arc_swap;
 #[macro_use]
 extern crate event_monitor;
-extern crate hypervisor;
-extern crate option_parser;
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
 extern crate log;
-extern crate serde;
 #[macro_use]
 extern crate serde_derive;
-extern crate serde_json;
-extern crate vmm_sys_util;
 #[cfg(test)]
 #[macro_use]
 extern crate credibility;

vmm/src/memory_manager.rs

@@ -2,7 +2,6 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 //
-extern crate hypervisor;
 #[cfg(target_arch = "x86_64")]
 use crate::config::SgxEpcConfig;
 use crate::config::{HotplugMethod, MemoryConfig, MemoryZoneConfig};

vmm/src/vm.rs

@@ -11,17 +11,6 @@
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 //
 
-extern crate arch;
-extern crate devices;
-extern crate epoll;
-extern crate hypervisor;
-extern crate libc;
-extern crate linux_loader;
-extern crate net_util;
-extern crate signal_hook;
-extern crate vm_allocator;
-extern crate vm_memory;
-
 #[cfg(feature = "acpi")]
 use crate::config::NumaConfig;
 use crate::config::{