message: do not delete DLLs when cleaning OUT_DIR
diff: @@ -549,7 +549,12 @@ fn build_wrapper(opencv_header_dir: &PathBuf) -> Result<()> {
  eprintln!("=== Generating code in: {}", out_dir_as_str);
  for entry in glob(&format!("{}/*", out_dir_as_str))? {
  - let _ = fs::remove_file(entry?);
  + let path = entry?;
  + let path = match path.extension().unwrap_or_default().to_str() {
  + Some("dll") => continue,
  + _ => path
  + };
  + let _ = fs::remove_file(path);
  }
  let modules = get_modules(&opencv_dir.to_string_lossy())?;
  