Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/net_bind_resource.rs

@@ -0,0 +1,14 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support panic recovery or bind
+
+use tokio::net::TcpListener;
+
+use std::convert::TryFrom;
+use std::net;
+
+#[test]
+#[should_panic]
+fn no_runtime_panics_binding_net_tcp_listener() {
+    let listener = net::TcpListener::bind("127.0.0.1:0").expect("failed to bind listener");
+    let _ = TcpListener::try_from(listener);
+}