Add back API removed recently Add hb_ot_layout_language_get_required_feature_index() again, which is used in Pango. This was removed in da132937989acb4d8ca9bd41c79f98750e7dda30 in favor of hb_ot_layout_language_get_required_feature(). API changes: - Added hb_ot_layout_language_get_required_feature_index back.