(match_ctx_free_subtops, search_cur_bkref_entry, match_ctx_add_sublast, sift_ctx_init, acquire_init_state_context, prune_impossible_nodes, check_halt_state_context, proceed_next_node, sift_states_backward, update_cur_sifted_state, check_dst_limits, check_dst_limits_calc_pos, sift_states_bkref, transit_state, check_subexp_matching_top, transit_state_sb, transit_state_mb, transit_state_bkref, get_subexp, get_subexp_sub, check_arrival, check_arrival_add_next_nodes, expand_bkref_cache, check_node_accept): Remove dfa parameter. Get dfa from mctxt. Adjust callers. (re_search_internal): Initialize mctxt.dfa.