(update_cur_sifted_state): Likewise.

(update_cur_sifted_state): Likewise.

	(re_search_internal): Likewise.
	(prune_impossible_nodes): Likewise.
	(acquire_init_state_context): Likewise.
	(proceed_next_node): Likewise.
	(set_regs): Likewise.
	(free_fail_stack_return): Likewise.
	(check_subexp_limits): Likewise.
	(sub_epsilon_src_nodes):  Likewise.
	(add_epsilon_src_nodes):  Likewise.
	(merge_state_array): Likewise.
	(update_regs): Likewise.
	(build_trtable): Likewise.
	(sift_states_backward): Mark MCTX parameter as const.
	(build_sifted_states): Likewise.
	(update_cur_sifted_state): Likewise.
	(sift_states_mkref): Likewise.
	(check_dst_limits_calc_pos_1): Likewise.
	* posix/regex_internal.h (re_match_context_t): Make dfa a const
	pointer.