build: Address issues found by 1.43.0 clippy

These are mostly due to use of "bare use" statements and unnecessary vector
creation.

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

vm-virtio/src/vhost_user/blk.rs

@@ -8,7 +8,6 @@ use super::Error as DeviceError;
 use super::{Error, Result};
 use crate::block::VirtioBlockConfig;
 use crate::VirtioInterrupt;
-use libc;
 use libc::EFD_NONBLOCK;
 use std::cmp;
 use std::io::Write;

vm-virtio/src/vhost_user/handler.rs

@@ -9,7 +9,6 @@
 
 use super::super::{Queue, VirtioInterruptType};
 use super::{Error, Result};
-use epoll;
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::VirtioInterrupt;

vm-virtio/src/vhost_user/mod.rs

@@ -7,7 +7,6 @@ extern crate vhost_rs;
 extern crate virtio_bindings;
 extern crate vm_memory;
 
-use std;
 use std::io;
 use vhost_rs::Error as VhostError;
 use vm_memory::Error as MmapError;

vm-virtio/src/vhost_user/net.rs

@@ -11,7 +11,6 @@ use super::vu_common_ctrl::*;
 use super::Error as DeviceError;
 use super::{Error, Result};
 use crate::VirtioInterrupt;
-use libc;
 use libc::EFD_NONBLOCK;
 use net_util::MacAddr;
 use std::cmp;

vm-virtio/src/vhost_user/vu_common_ctrl.rs

@@ -1,25 +1,21 @@
 // Copyright 2019 Intel Corporation. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use libc;
+use super::super::Queue;
+use super::{Error, Result};
+use crate::queue::Descriptor;
+use crate::{VirtioInterrupt, VirtioInterruptType};
 use libc::EFD_NONBLOCK;
 use std::convert::TryInto;
 use std::os::unix::io::AsRawFd;
 use std::sync::Arc;
 use std::vec::Vec;
-
-use crate::queue::Descriptor;
-use crate::{VirtioInterrupt, VirtioInterruptType};
-
+use vhost_rs::vhost_user::{Master, VhostUserMaster};
+use vhost_rs::{VhostBackend, VhostUserMemoryRegionInfo, VringConfigData};
 use vm_device::get_host_address_range;
 use vm_memory::{Address, Error as MmapError, GuestMemory, GuestMemoryMmap, GuestMemoryRegion};
 use vmm_sys_util::eventfd::EventFd;
 
-use super::super::Queue;
-use super::{Error, Result};
-use vhost_rs::vhost_user::{Master, VhostUserMaster};
-use vhost_rs::{VhostBackend, VhostUserMemoryRegionInfo, VringConfigData};
-
 #[derive(Debug, Clone)]
 pub struct VhostUserConfig {
     pub sock: String,