message: refactor(client): use `Box<str>` inside `dns::Name`
  Use Box<str> in hyper::client::connect::dns::Name, so
  its size is 16 bytes, not 24 bytes.  As Name never
  change its contents, read-only Box<str> is perfectly OK.
diff: @@ -38,7 +38,7 @@ pub(super) use self::sealed::Resolve;
  /// A domain name to resolve into IP addresses.
  #[derive(Clone, Hash, Eq, PartialEq)]
  pub struct Name {
  - host: String,
  + host: Box<str>,
  }
  /// A resolver using blocking `getaddrinfo` calls in a threadpool.
  @@ -58,7 +58,7 @@ pub struct GaiFuture {
  }
  impl Name {
  - pub(super) fn new(host: String) -> Name {
  + pub(super) fn new(host: Box<str>) -> Name {
  Name { host }
  }
  @@ -85,7 +85,7 @@ impl FromStr for Name {
  fn from_str(host: &str) -> Result<Self, Self::Err> {
  // Possibly add validation later
  - Ok(Name::new(host.to_owned()))
  + Ok(Name::new(host.into()))
  }
  }
  