strip Default from Config and CiEnv

Author: Shunpoco

src/bootstrap/src/core/config/config.rs

@@ -88,7 +88,7 @@ pub const RUSTC_IF_UNCHANGED_ALLOWED_PATHS: &[&str] = &[
 /// filled out from the decoded forms of the structs below. For documentation
 /// on each field, see the corresponding fields in
 /// `bootstrap.example.toml`.
-#[derive(Default, Clone)]
+#[derive(Clone)]
 pub struct Config {
     pub change_id: Option<ChangeId>,
     pub bypass_bootstrap_lock: bool,

src/build_helper/src/ci.rs

@@ -1,7 +1,6 @@
-#[derive(Copy, Clone, PartialEq, Eq, Debug, Default)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum CiEnv {
     /// Not a CI environment.
-    #[default]
     None,
     /// The GitHub Actions environment, for Linux (including Docker), Windows and macOS builds.
     GitHubActions,