c-family/
	* c-common.h (c_omp_mark_declare_variant,
	c_omp_context_selector_matches): Declare.
	* c-omp.c: Include attribs.h, gimplify.h, cgraph.h, symbol-summary.h
	and hsa-common.h.
	(c_omp_get_context_selector): Support second argument NULL.
	(c_omp_mark_declare_variant, c_omp_context_selector_matches): New
	functions.
	* c-attribs.c (c_common_attribute_table): Remove "omp declare variant"
	attribute, add "omp declare variant base" and
	"omp declare variant variant" attributes.
c/
	* c-parser.c (c_parser_omp_context_selector): Improve error recovery.
	For simd properties, put them directly into TREE_VALUE.
	(c_finish_omp_declare_variant): Call c_omp_mark_declare_variant.
	If c_omp_context_selector_matches is 0, don't add attribute, otherwise
	add "omp declare variant base" attribute rather than
	"omp declare variant".
cp/
	* parser.c (cp_parser_omp_context_selector): Improve error recovery.
	For simd properties, put them directly into TREE_VALUE.
	(cp_finish_omp_declare_variant): Add "omp declare variant base"
	attribute rather than "omp declare variant".
testsuite/
	* c-c++-common/gomp/declare-variant-2.c: Adjust for error recovery
	improvements.  Add new tests.
	* c-c++-common/gomp/declare-variant-4.c: New test.
	* c-c++-common/gomp/declare-variant-5.c: New test.
	* c-c++-common/gomp/declare-variant-6.c: New test.
	* c-c++-common/gomp/declare-variant-7.c: New test.

From-SVN: r276914