Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/signal_notify_both.rs

@@ -0,0 +1,23 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+#![cfg(unix)]
+
+mod support {
+    pub mod signal;
+}
+use support::signal::send_signal;
+
+use tokio::signal::unix::{signal, SignalKind};
+
+#[tokio::test]
+async fn notify_both() {
+    let kind = SignalKind::user_defined2();
+
+    let mut signal1 = signal(kind).expect("failed to create signal1");
+    let mut signal2 = signal(kind).expect("failed to create signal2");
+
+    send_signal(libc::SIGUSR2);
+
+    signal1.recv().await;
+    signal2.recv().await;
+}