libstdc++: Remove redundant -std=gnu++17 option from remaining tests

libstdc++: Remove redundant -std=gnu++17 option from remaining tests

GCC defaults to -std=gnu++17 now anyway, and using it explicitly in the
dg-options directive prevents running these tests with different modes
such as -std=c++17 or -std=gnu++20.

libstdc++-v3/ChangeLog:

	* testsuite/17_intro/headers/c++2017/all_attributes.cc: Remove
	-std=gnu++17 from dg-options directive.
	* testsuite/17_intro/headers/c++2017/all_no_exceptions.cc:
	Likewise.
	* testsuite/17_intro/headers/c++2017/all_pedantic_errors.cc:
	Likewise.
	* testsuite/17_intro/headers/c++2017/operator_names.cc:
	Likewise.
	* testsuite/17_intro/headers/c++2017/parallel_mode.cc: Likewise.
	* testsuite/17_intro/headers/c++2017/stdc++.cc: Likewise.
	* testsuite/17_intro/headers/c++2017/stdc++_multiple_inclusion.cc:
	Likewise.
	* testsuite/18_support/aligned_alloc/aligned_alloc.cc: Likewise.
	* testsuite/18_support/byte/81076.cc: Likewise.
	* testsuite/18_support/byte/global_neg.cc: Likewise.
	* testsuite/18_support/byte/ops.cc: Likewise.
	* testsuite/18_support/byte/requirements.cc: Likewise.
	* testsuite/18_support/headers/cfloat/values_c++17.cc: Likewise.
	* testsuite/18_support/launder/1.cc: Likewise.
	* testsuite/18_support/launder/nodiscard.cc: Likewise.
	* testsuite/18_support/launder/requirements.cc: Likewise.
	* testsuite/18_support/launder/requirements_neg.cc: Likewise.
	* testsuite/18_support/new_aligned.cc: Likewise.
	* testsuite/18_support/uncaught_exceptions/uncaught_exceptions.cc:
	Likewise.
	* testsuite/19_diagnostics/error_code/is_error_code_v.cc:
	Likewise.
	* testsuite/19_diagnostics/error_condition/hash.cc: Likewise.
	* testsuite/20_util/addressof/requirements/constexpr.cc:
	Likewise.
	* testsuite/20_util/as_const/1.cc: Likewise.
	* testsuite/20_util/as_const/rvalue_neg.cc: Likewise.
	* testsuite/20_util/bind/83427.cc: Likewise.
	* testsuite/20_util/bind/is_placeholder_v.cc: Likewise.
	* testsuite/20_util/bool_constant/requirements.cc: Likewise.
	* testsuite/20_util/duration/arithmetic/constexpr_c++17.cc:
	Likewise.
	* testsuite/20_util/duration/requirements/treat_as_floating_point_v.cc:
	Likewise.
	* testsuite/20_util/duration_cast/rounding.cc: Likewise.
	* testsuite/20_util/enable_shared_from_this/members/weak_from_this.cc:
	Likewise.
	* testsuite/20_util/from_chars/1_neg.cc: Likewise.
	* testsuite/20_util/from_chars/requirements.cc: Likewise.
	* testsuite/20_util/function/91456.cc: Likewise.
	* testsuite/20_util/function/cons/deduction.cc: Likewise.
	* testsuite/20_util/function_objects/83607.cc: Likewise.
	* testsuite/20_util/function_objects/invoke/59768.cc: Likewise.
	* testsuite/20_util/function_objects/mem_fn/80478.cc: Likewise.
	* testsuite/20_util/function_objects/not_fn/1.cc: Likewise.
	* testsuite/20_util/function_objects/not_fn/87538.cc: Likewise.
	* testsuite/20_util/has_unique_object_representations/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/has_unique_object_representations/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/has_unique_object_representations/value.cc:
	Likewise.
	* testsuite/20_util/hash/nullptr.cc: Likewise.
	* testsuite/20_util/in_place/requirements.cc: Likewise.
	* testsuite/20_util/is_aggregate/incomplete_neg.cc: Likewise.
	* testsuite/20_util/is_aggregate/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_aggregate/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_aggregate/value.cc: Likewise.
	* testsuite/20_util/is_invocable/83395.cc: Likewise.
	* testsuite/20_util/is_invocable/91456.cc: Likewise.
	* testsuite/20_util/is_invocable/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_invocable/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_invocable/value.cc: Likewise.
	* testsuite/20_util/is_literal_type/deprecated-1z.cc: Likewise.
	* testsuite/20_util/is_nothrow_constructible/94003.cc: Likewise.
	* testsuite/20_util/is_nothrow_invocable/83395.cc: Likewise.
	* testsuite/20_util/is_nothrow_invocable/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_nothrow_invocable/requirements/typedefs.cc: Likewise.
	* testsuite/20_util/is_nothrow_invocable/value.cc: Likewise.
	* testsuite/20_util/is_nothrow_swappable/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_nothrow_swappable/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_nothrow_swappable/value.cc: Likewise.
	* testsuite/20_util/is_nothrow_swappable_with/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_nothrow_swappable_with/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_nothrow_swappable_with/value.cc:
	Likewise.
	* testsuite/20_util/is_swappable/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_swappable/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_swappable/value.cc: Likewise.
	* testsuite/20_util/is_swappable_with/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/is_swappable_with/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_swappable_with/value.cc: Likewise.
	* testsuite/20_util/logical_traits/83134.cc: Likewise.
	* testsuite/20_util/logical_traits/requirements/explicit_instantiation.cc:
	Likewise.
	* testsuite/20_util/logical_traits/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/logical_traits/value.cc: Likewise.
	* testsuite/20_util/pair/cons/deduction.cc: Likewise.
	* testsuite/20_util/pair/swap_cxx17.cc: Likewise.
	* testsuite/20_util/ratio/requirements/ratio_equal_v.cc:
	Likewise.
	* testsuite/20_util/reference_wrapper/83427.cc: Likewise.
	* testsuite/20_util/reference_wrapper/deduction.cc: Likewise.
	* testsuite/20_util/shared_ptr/casts/reinterpret.cc: Likewise.
	* testsuite/20_util/shared_ptr/cons/deduction.cc: Likewise.
	* testsuite/20_util/shared_ptr/requirements/weak_type.cc:
	Likewise.
	* testsuite/20_util/time_point/arithmetic/constexpr.cc:
	Likewise.
	* testsuite/20_util/time_point_cast/rounding.cc: Likewise.
	* testsuite/20_util/to_chars/3.cc: Likewise.
	* testsuite/20_util/to_chars/chars_format.cc: Likewise.
	* testsuite/20_util/to_chars/lwg3266.cc: Likewise.
	* testsuite/20_util/to_chars/requirements.cc: Likewise.
	* testsuite/20_util/tuple/78939.cc: Likewise.
	* testsuite/20_util/tuple/apply/1.cc: Likewise.
	* testsuite/20_util/tuple/apply/2.cc: Likewise.
	* testsuite/20_util/tuple/cons/deduction.cc: Likewise.
	* testsuite/20_util/tuple/make_from_tuple/1.cc: Likewise.
	* testsuite/20_util/tuple/make_from_tuple/2.cc: Likewise.
	* testsuite/20_util/tuple/swap_cxx17.cc: Likewise.
	* testsuite/20_util/tuple/tuple_size_v.cc: Likewise.
	* testsuite/20_util/unique_ptr/cons/deduction_neg.cc: Likewise.
	* testsuite/20_util/uses_allocator/requirements/uses_allocator_v.cc:
	Likewise.
	* testsuite/20_util/variable_templates_for_traits.cc: Likewise.
	* testsuite/20_util/void_t/1.cc: Likewise.
	* testsuite/20_util/weak_ptr/cons/deduction.cc: Likewise.
	* testsuite/24_iterators/container_access.cc: Likewise.
	* testsuite/24_iterators/headers/iterator/range_access_c++17.cc:
	Likewise.
	* testsuite/24_iterators/headers/iterator/synopsis_c++17.cc:
	Likewise.
	* testsuite/24_iterators/range_access/range_access_cpp17.cc:
	Likewise.
	* testsuite/24_iterators/range_access/range_access_cpp17_neg.cc:
	Likewise.
	* testsuite/26_numerics/gcd/gcd_neg.cc: Likewise.
	* testsuite/26_numerics/headers/cmath/functions_std_c++17.cc:
	Likewise.
	* testsuite/26_numerics/headers/cmath/hypot.cc: Likewise.
	* testsuite/26_numerics/headers/cmath/special_functions_global.cc:
	Likewise.
	* testsuite/26_numerics/lcm/1.cc: Likewise.
	* testsuite/26_numerics/lcm/lcm_neg.cc: Likewise.
	* testsuite/26_numerics/valarray/deduction.cc: Likewise.
	* testsuite/27_io/basic_ostream/inserters_other/char/lwg2221.cc:
	Likewise.
	* testsuite/27_io/manipulators/standard/char/quoted_sv.cc:
	Likewise.
	* testsuite/27_io/manipulators/standard/wchar_t/quoted_sv.cc:
	Likewise.
	* testsuite/27_io/types/4.cc: Likewise.
	* testsuite/28_regex/basic_regex/ctors/deduction.cc: Likewise.
	* testsuite/libstdc++-prettyprinters/91997.cc: Likewise.
	* testsuite/libstdc++-prettyprinters/cxx17.cc: Likewise.