* omp-general.h (omp_context_selector_set_compare): Declare.
	* omp-general.c (omp_construct_simd_compare,
	omp_context_selector_props_compare, omp_context_selector_set_compare,
	omp_context_selector_compare): New functions.
	(omp_resolve_declare_variant): Prune variants that are strict subset
	of another variant.
c-family/
	* c-omp.c (c_omp_mark_declare_variant): Use
	omp_context_selector_set_compare.
testsuite/
	* c-c++-common/gomp/declare-variant-6.c: Expect construct rather than
	constructor in diagnostic messages.
	* c-c++-common/gomp/declare-variant-7.c: Likewise.
	* c-c++-common/gomp/declare-variant-11.c: New test.

From-SVN: r277734