chore: remove tokio-futures facade crate (#1327)

This switches from using the tokio-futures facade to referencing
futures-* crates directly.

tokio-codec/src/macros.rs

@@ -1,18 +1,3 @@
-// TODO this macro should probably be somewhere in tokio-futures
-/// A macro for extracting the successful type of a `Poll<T, E>`.
-///
-/// This macro bakes propagation of both errors and `Pending` signals by
-/// returning early.
-macro_rules! try_ready {
-    ($e:expr) => {
-        match $e {
-            std::task::Poll::Pending => return std::task::Poll::Pending,
-            std::task::Poll::Ready(Err(e)) => return std::task::Poll::Ready(Err(From::from(e))),
-            std::task::Poll::Ready(Ok(t)) => t,
-        }
-    };
-}
-
 /// A macro to reduce some of the boilerplate for projecting from
 /// `Pin<&mut T>` to `Pin<&mut T.field>`
 macro_rules! pin {