message: Exclude empty elements from env var lists
diff: @@ -257,7 +257,7 @@ impl Library {
  } else {
  vec![]
  };
  - includes.extend(include_paths.iter().map(T::from));
  + includes.extend(include_paths.iter().filter(|v| !v.is_empty()).map(T::from));
  includes
  } else {
  sys_list
  