io: move into `tokio` crate (#1691)

A step towards collapsing Tokio sub crates into a single `tokio`
crate (#1318).

The `io` implementation is now provided by the main `tokio` crate.
Functionality can be opted out of by using the various net related
feature flags.

1 files changed, 4 insertions, 0 deletions

diff --git a/tokio/src/lib.rs b/tokio/src/lib.rs
index 814f2a59..249bf47a 100644
--- a/tokio/src/lib.rs
+++ b/tokio/src/lib.rs
@@ -129,3 +129,7 @@ if_runtime! {
     #[doc(inline)]
     pub use tokio_macros::test;
 }
+
+#[cfg(feature = "io-util")]
+#[cfg(test)]
+fn is_unpin<T: Unpin>() {}