chore: use ready macro from futures-core (#1300)

tokio-sync/tests/fuzz_oneshot.rs

@@ -1,19 +1,6 @@
 #![deny(warnings, rust_2018_idioms)]
 #![feature(async_await)]
 
-/// Unwrap a ready value or propagate `Async::Pending`.
-#[macro_export]
-macro_rules! ready {
-    ($e:expr) => {{
-        use std::task::Poll::{Pending, Ready};
-
-        match $e {
-            Ready(v) => v,
-            Pending => return Pending,
-        }
-    }};
-}
-
 #[path = "../src/oneshot.rs"]
 #[allow(warnings)]
 mod oneshot;