Merge "Create $(findstring) starlark implementation"

    return sorted(["%s/%s:%s/%s" % (

        from_dir, f, to_dir, f) for f in rblf_find_files(from_dir, pattern, only_files=1)])

def _findstring(needle, haystack):

    """Equivalent to GNU make's $(findstring)."""

    if haystack.find(needle) < 0:

        return ""

    return needle

def _filter_out(pattern, text):

    """Return all the words from `text' that do not match any word in `pattern'.

    filter = _filter,

    filter_out = _filter_out,

    find_and_copy = _find_and_copy,

    findstring = _findstring,

    inherit = _inherit,

    indirect = _indirect,

    mk2rbc_error = _mk2rbc_error,