Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/signal_ctrl_c.rs

@@ -0,0 +1,30 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+#![cfg(unix)]
+
+mod support {
+    pub mod signal;
+}
+use support::signal::send_signal;
+
+use tokio::signal;
+use tokio::sync::oneshot;
+use tokio_test::assert_ok;
+
+#[tokio::test]
+async fn ctrl_c() {
+    let ctrl_c = signal::ctrl_c();
+
+    let (fire, wait) = oneshot::channel();
+
+    // NB: simulate a signal coming in by exercising our signal handler
+    // to avoid complications with sending SIGINT to the test process
+    tokio::spawn(async {
+        wait.await.expect("wait failed");
+        send_signal(libc::SIGINT);
+    });
+
+    let _ = fire.send(());
+
+    assert_ok!(ctrl_c.await);
+}