message: `map_dependencies` is doing a deep clone, so lets make it cheaper
diff: @@ -26,7 +26,7 @@ pub struct Summary {
  struct Inner {
  package_id: PackageId,
  dependencies: Vec<Dependency>,
  - features: FeatureMap,
  + features: Rc<FeatureMap>,
  checksum: Option<String>,
  links: Option<InternedString>,
  namespaced_features: bool,
  @@ -64,7 +64,7 @@ impl Summary {
  inner: Rc::new(Inner {
  package_id: pkg_id,
  dependencies,
  - features: feature_map,
  + features: Rc::new(feature_map),
  checksum: None,
  links: links.map(|l| l.into()),
  namespaced_features,
  