chore: move enumerate test to correct location (#867)

tokio-timer/tests/enumerate.rs

@@ -1,31 +0,0 @@
-extern crate futures;
-extern crate tokio;
-extern crate tokio_executor;
-extern crate tokio_timer;
-
-#[macro_use]
-mod support;
-
-use futures::prelude::*;
-use futures::sync::mpsc;
-use tokio::util::StreamExt;
-
-#[test]
-fn enumerate() {
-    use futures::*;
-
-    let (mut tx, rx) = mpsc::channel(1);
-
-    std::thread::spawn(|| {
-        for i in 0..5 {
-            tx = tx.send(i * 2).wait().unwrap();
-        }
-    });
-
-    let mut result = rx.enumerate().collect();
-    assert_eq!(
-        result.wait(),
-        Ok(vec![(0, 0), (1, 2), (2, 4), (3, 6), (4, 8)])
-    );
-
-}