message: h3: pass a slice instead of a reference to a vec for a few fns
diff: @@ -54,7 +54,7 @@ impl Request {
  scheme: &str,
  host: &str,
  path: &str,
  - headers: &Vec<(String, String)>,
  + headers: &[(String, String)],
  ) -> Request {
  let mut r = Request {
  method: method.to_owned(),
  @@ -68,7 +68,7 @@ impl Request {
  r.headers.push((":scheme".into(), r.scheme.clone()));
  r.headers.push((":authority".into(), r.host.clone()));
  r.headers.push((":path".into(), r.path.clone()));
  - r.headers.extend_from_slice(&headers);
  + r.headers.extend_from_slice(headers);
  r
  }
  @@ -157,7 +157,7 @@ impl ClientRequest {
  scheme: &str,
  host: &str,
  path: &str,
  - headers: &Vec<(String, String)>,
  + headers: &[(String, String)],
  ) -> ClientRequest {
  qdebug!("Create a request stream_id={}", stream_id);
  ClientRequest {
  @@ -681,7 +681,7 @@ impl HttpConn {
  scheme: &str,
  host: &str,
  path: &str,
  - headers: &Vec<(String, String)>,
  + headers: &[(String, String)],
  ) -> Res<()> {
  let id = self.conn.stream_create(StreamType::BiDi)?;
  self.client_requests.insert(
  