tidy-up: miscellaneous

- tool_bname: scope an include.
- `endif` comments.
- Markdown fixes.
- comment tidy-ups.
- whitespace, newlines, indent.

Closes #20309

lib/formdata.c

@@ -840,8 +840,7 @@ CURLcode Curl_getformdata(CURL *data,
   return result;
 }
 
-#else
-/* if disabled */
+#else /* if disabled */
 CURLFORMcode curl_formadd(struct curl_httppost **httppost,
                           struct curl_httppost **last_post, ...)
 {