Silence clippy::unused_io_amount in various places

Way too many false positives.

Backport of 8a1bfe1

examples/tcp_listenfd_server.rs

@@ -125,6 +125,7 @@ fn next(current: &mut Token) -> Token {
 }
 
 /// Returns `true` if the connection is done.
+#[allow(clippy::unused_io_amount)]
 fn handle_connection_event(
     registry: &Registry,
     connection: &mut TcpStream,

src/sys/unix/waker.rs

@@ -100,6 +100,7 @@ mod eventfd {
             Ok(WakerInternal { fd: file })
         }
 
+        #[allow(clippy::unused_io_amount)]
         pub fn wake(&self) -> io::Result<()> {
             let buf: [u8; 8] = 1u64.to_ne_bytes();
             match (&self.fd).write(&buf) {
@@ -120,6 +121,7 @@ mod eventfd {
         }
 
         /// Reset the eventfd object, only need to call this if `wake` fails.
+        #[allow(clippy::unused_io_amount)]
         fn reset(&self) -> io::Result<()> {
             let mut buf: [u8; 8] = 0u64.to_ne_bytes();
             match (&self.fd).read(&mut buf) {

tests/tcp.rs

@@ -584,6 +584,7 @@ fn connect_error() {
 }
 
 #[test]
+#[allow(clippy::unused_io_amount)]
 fn write_error() {
     init();