bootstrap: enable tidy auto extra checks on tools profile

bootstrap.example.toml

@@ -475,6 +475,9 @@
 # Note that if any value is manually given to bootstrap such as
 # `./x test tidy --extra-checks=js`, this value is ignored.
 # Use `--extra-checks=''` to temporarily disable all extra checks.
+#
+# Automatically enabled in the "tools" profile.
+# Set to the empty string to force disable (recommeded for hdd systems).
 #build.tidy-extra-checks = ""
 
 # Indicates whether ccache is used when building certain artifacts (e.g. LLVM).

src/bootstrap/defaults/bootstrap.tools.toml

@@ -14,6 +14,8 @@ test-stage = 2
 doc-stage = 2
 # Contributors working on tools will probably expect compiler docs to be generated, so they can figure out how to use the API.
 compiler-docs = true
+# Contributors working on tools are the most likely to change non-rust programs.
+tidy-extra-checks = "auto:js,auto:py,auto:cpp,auto:spellcheck"
 
 [llvm]
 # Will download LLVM from CI if available on your platform.