misc: Fix various clippy issues

Assisted-by: Claude:Opus-4.7
Signed-off-by: Bo Chen <bchen@crusoe.ai>

virtio-devices/src/vsock/unix/muxer.rs

@@ -407,9 +407,11 @@ impl VsockMuxer {
             Some(EpollListener::HostSock) => {
                 if self.conn_map.len() == defs::MAX_CONNECTIONS {
                     // If we're already maxed-out on connections, we'll just accept and
-                    // immediately discard this potentially new one.
+                    // immediately discard this potentially new one. Dropping the returned
+                    // `UnixStream` closes the new connection; we don't care if `accept()`
+                    // itself failed.
                     warn!("vsock: connection limit reached; refusing new host connection");
-                    self.host_sock.accept().map(|_| 0).unwrap_or(0);
+                    let _ = self.host_sock.accept();
                     return;
                 }
                 self.host_sock

virtio-devices/src/vsock/unix/muxer_killq.rs

@@ -110,6 +110,10 @@ impl MuxerKillQ {
     /// This will succeed and return a connection key, only if the connection at the front of
     /// the queue has expired. Otherwise, `None` is returned.
     ///
+    // `VecDeque::pop_front_if` is unstable on the project MSRV; allow the
+    // beta clippy lint that asks for it. `unknown_lints` is needed because
+    // the lint does not exist on stable clippy.
+    #[allow(unknown_lints, clippy::manual_pop_if)]
     pub fn pop(&mut self) -> Option<ConnMapKey> {
         if let Some(item) = self.q.front()
             && Instant::now() > item.kill_time