message: Add build script rerun-if-changed dependencies
  Also pick up the rerun-if-changed dependencies from build scripts.
diff: @@ -27,6 +27,7 @@ fn add_deps_for_unit<'a, 'b>(deps: &mut HashSet<PathBuf>, context: &mut Context<
  }
  visited.insert(unit.clone());
  + // Add dependencies from rustc dep-info output (stored in fingerprint directory)
  let dep_info_loc = fingerprint::dep_info_loc(context, unit);
  if let Some(paths) = fingerprint::parse_dep_info(&dep_info_loc)? {
  for path in paths {
  @@ -34,7 +35,15 @@ fn add_deps_for_unit<'a, 'b>(deps: &mut HashSet<PathBuf>, context: &mut Context<
  }
  }
  - // recursively traverse all transitive dependencies
  + // Add rerun-if-changed dependencies
  + let key = (unit.pkg.package_id().clone(), unit.kind);
  + if let Some(output) = context.build_state.outputs.lock().unwrap().get(&key) {
  + for path in &output.rerun_if_changed {
  + deps.insert(path.into());
  + }
  + }
  +
  + // Recursively traverse all transitive dependencies
  for dep_unit in &context.dep_targets(unit)? {
  let source_id = dep_unit.pkg.package_id().source_id();
  if source_id.is_path() {
  