openmp: Diagnose another case of mixing parameter and attribute syntax

openmp: Diagnose another case of mixing parameter and attribute syntax

This patch diagnoses cases like:
  #pragma omp parallel
  [[omp::directive (declare simd)]] int foo ();
or
  #pragma omp taskgroup
  int bar [[omp::directive (declare simd)]] (int);
where the pragma is on the same declaration statement as the declare simd
attribute.

2021-08-12  Jakub Jelinek  <jakub@redhat.com>

	* parser.c (cp_parser_lambda_body): Add temp overrides
	for parser->{omp_declare_simd,oacc_routine,omp_attrs_forbidden_p}.
	(cp_parser_statement): Restore parser->omp_attrs_forbidden_p for
	cp_parser_declaration_statement.
	(cp_parser_default_argument): Add temp override for
	parser->omp_attrs_forbidden_p.
	(cp_parser_late_parsing_omp_declare_simd): Diagnose declare simd
	or declare variant in attribute syntax on a declaration immediately
	following an OpenMP construct in pragma syntax.

	* g++.dg/gomp/attrs-11.C: Add new tests.