libstdc++: Support skip, only, expensive, and xfail markers for simd tests

libstdc++: Support skip, only, expensive, and xfail markers for simd tests

libstdc++-v3/ChangeLog:

	* testsuite/experimental/simd/driver.sh: Implement skip, only,
	expensive, and xfail markers. They can select on type, ABI tag
	subset number, target-triplet, and compiler flags.
	* testsuite/experimental/simd/generate_makefile.sh: The summary
	now includes lines for unexpected passes and expected failures.
	If the skip or only markers are only conditional on the type, do
	not generate rules for those types.
	* testsuite/experimental/simd/tests/abs.cc: Mark test expensive
	for ABI tag subsets 1-9.
	* testsuite/experimental/simd/tests/algorithms.cc: Ditto.
	* testsuite/experimental/simd/tests/broadcast.cc: Ditto.
	* testsuite/experimental/simd/tests/casts.cc: Ditto.
	* testsuite/experimental/simd/tests/generator.cc: Ditto.
	* testsuite/experimental/simd/tests/integer_operators.cc: Ditto.
	* testsuite/experimental/simd/tests/loadstore.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_broadcast.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_conversions.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_implicit_cvt.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_loadstore.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_operator_cvt.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_operators.cc: Ditto.
	* testsuite/experimental/simd/tests/mask_reductions.cc: Ditto.
	* testsuite/experimental/simd/tests/operator_cvt.cc: Ditto.
	* testsuite/experimental/simd/tests/operators.cc: Ditto.
	* testsuite/experimental/simd/tests/reductions.cc: Ditto.
	* testsuite/experimental/simd/tests/simd.cc: Ditto.
	* testsuite/experimental/simd/tests/split_concat.cc: Ditto.
	* testsuite/experimental/simd/tests/splits.cc: Ditto.
	* testsuite/experimental/simd/tests/where.cc: Ditto.
	* testsuite/experimental/simd/tests/fpclassify.cc: Ditto. In
	addition replace "test only floattypes" marker by unconditional
	"float|double|ldouble" only marker.
	* testsuite/experimental/simd/tests/frexp.cc: Ditto.
	* testsuite/experimental/simd/tests/hypot3_fma.cc: Ditto.
	* testsuite/experimental/simd/tests/ldexp_scalbn_scalbln_modf.cc:
	Ditto.
	* testsuite/experimental/simd/tests/logarithm.cc: Ditto.
	* testsuite/experimental/simd/tests/math_1arg.cc: Ditto.
	* testsuite/experimental/simd/tests/math_2arg.cc: Ditto.
	* testsuite/experimental/simd/tests/remqo.cc: Ditto.
	* testsuite/experimental/simd/tests/trigonometric.cc: Ditto.
	* testsuite/experimental/simd/tests/trunc_ceil_floor.cc: Ditto.
	* testsuite/experimental/simd/tests/sincos.cc: Ditto. In
	addition, xfail on run because the reference data is missing.