Fix warnings and errors from beta Rust (#2904)

examples/serve-with-hyper/src/main.rs

@@ -11,6 +11,8 @@
 //!
 //! [hyper-util]: https://crates.io/crates/hyper-util
 
+#![allow(unreachable_patterns)]
+
 use std::convert::Infallible;
 use std::net::SocketAddr;
 

examples/unix-domain-socket/src/main.rs

@@ -3,6 +3,7 @@
 //! ```not_rust
 //! cargo run -p example-unix-domain-socket
 //! ```
+#![allow(unreachable_patterns)]
 
 #[cfg(unix)]
 #[tokio::main]