Macro rustls::check::require_handshake_msg

macro_rules! require_handshake_msg {
    ( $m:expr, $handshake_type:path, $payload_type:path ) => { ... };
}

For a Message $m, and a HandshakePayload enum member $payload_type, return Ok(payload) if $m is both a handshake message and one that has the given $payload_type. If not, return Err(rustls::Error) quoting $handshake_type as the expected handshake type.