openmp: Reject requires directives not at file or namespace scope [PR94593]

openmp: Reject requires directives not at file or namespace scope [PR94593]

This change started with a bugreport about a typo in one requires testcase
(diagnosed with -Wunknown-pragmas only), but following discussion lead to
noting that we do not diagnose restriction that requires directives in
C/C++ may only appear at file or namespace scope; and several our tests
violated that.

2020-04-15  Jakub Jelinek  <jakub@redhat.com>

	PR c/94593
	* c-parser.c (c_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
	requires directive when not at file scope.

	* parser.c (cp_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
	requires directive when not at file or namespace scope.

	* c-c++-common/gomp/requires-1.c: Fix a typo, requries -> requires.
	Move directives to file scope.
	(i): Remove.
	* c-c++-common/gomp/requires-2.c: Move directives to file scope.
	(i, foo): Remove.
	* c-c++-common/gomp/requires-4.c: Move directives to file scope.
	* c-c++-common/gomp/atomic-19.c: Move requires directive to file scope.
	* c-c++-common/gomp/atomic-20.c: Likewise.
	* c-c++-common/gomp/atomic-21.c: Likewise.
	* c-c++-common/gomp/atomic-22.c: Likewise.
	* gcc.dg/gomp/requires-1.c: New test.
	* g++.dg/gomp/requires-1.C: New test.
	* g++.dg/gomp/requires-2.C: New test.
	* g++.dg/gomp/atomic-18.C: Move requires directive to file scope.