misc: clippy: add needless_pass_by_value

This is a follow-up of [0].

# Advantages

- This saves dozens of unneeded clone()s across the whole code base
- Makes it much easier to reason about how parameters are used
  (often we passed owned Arc/Rc versions without actually needing
  ownership)

# Exceptions

For certain code paths, the alternatives would require awkward or overly
complex code, and in some cases the functions are the logical owners of
the values they take. In those cases, I've added
#[allow(clippy::needless_pass_by_value)].

This does not mean that one should not improve this in the future.

[0] 6a86c157af

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

virtio-devices/src/epoll_helper.rs

@@ -10,8 +10,8 @@
 
 use std::fs::File;
 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
+use std::sync::Barrier;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Arc, Barrier};
 use std::thread;
 
 use log::info;
@@ -153,8 +153,8 @@ impl EpollHelper {
 
     pub fn run(
         &mut self,
-        paused: Arc<AtomicBool>,
-        paused_sync: Arc<Barrier>,
+        paused: &AtomicBool,
+        paused_sync: &Barrier,
         handler: &mut dyn EpollHelperHandler,
     ) -> std::result::Result<(), EpollHelperError> {
         self.run_with_timeout(paused, paused_sync, handler, -1, false)
@@ -163,8 +163,8 @@ impl EpollHelper {
     #[cfg(not(fuzzing))]
     pub fn run_with_timeout(
         &mut self,
-        paused: Arc<AtomicBool>,
-        paused_sync: Arc<Barrier>,
+        paused: &AtomicBool,
+        paused_sync: &Barrier,
         handler: &mut dyn EpollHelperHandler,
         timeout: i32,
         enable_event_list: bool,
@@ -250,8 +250,8 @@ impl EpollHelper {
     // and return when no epoll events are active
     pub fn run_with_timeout(
         &mut self,
-        paused: Arc<AtomicBool>,
-        paused_sync: Arc<Barrier>,
+        paused: &AtomicBool,
+        paused_sync: &Barrier,
         handler: &mut dyn EpollHelperHandler,
         _timeout: i32,
         _enable_event_list: bool,