Merge branch 'lt/dir-cleanup'

* lt/dir-cleanup: Make index preloading check the whole path to the file Export thread-safe version of 'has_symlink_leading_path()' Prepare symlink caching for thread-safety Avoid using 'lstat()' to figure out directories Avoid doing extra 'lstat()'s for d_type if we have an up-to-date cache entry Simplify read_directory[_recursive]() arguments Add 'fill_directory()' helper function for directory traversal