bootstrap: rust-installer no loger subtree, so allow running lints over it

Author: klensy

src/bootstrap/tool.rs

@@ -289,7 +289,7 @@ bootstrap_tool!(
     Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true, allow_features = "test";
     BuildManifest, "src/tools/build-manifest", "build-manifest";
     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
-    RustInstaller, "src/tools/rust-installer", "rust-installer", is_external_tool = true;
+    RustInstaller, "src/tools/rust-installer", "rust-installer";
     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes";
     ExpandYamlAnchors, "src/tools/expand-yaml-anchors", "expand-yaml-anchors";
     LintDocs, "src/tools/lint-docs", "lint-docs";