PR preprocessor/83063 - __VA_OPT__ and ##

PR preprocessor/83063 - __VA_OPT__ and ##

	PR preprocessor/83708
	* macro.c (vaopt_state): Reorder m_last_was_paste before m_state.
	(vaopt_state::vaopt_state): Adjust.
	(vaopt_state::update_flags): Add BEGIN and END.
	(vaopt_state::update): Return them.
	(copy_paste_flag): Factor out of replace_args.
	(last_token_is): New.
	(replace_args): Handle BEGIN and END.  Avoid padding there.
	(tokens_buff_last_token_ptr): Return NULL if no tokens.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>
From-SVN: r257696