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

libstdc++: Remove redundant -std=gnu++17 option from containers 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/23_containers/array/cons/deduction.cc: Remove
	-std=gnu++17 from dg-options directive.
	* testsuite/23_containers/array/cons/deduction_neg.cc: Likewise.
	* testsuite/23_containers/array/element_access/constexpr_c++17.cc:
	Likewise.
	* testsuite/23_containers/array/requirements/constexpr_iter.cc:
	Likewise.
	* testsuite/23_containers/array/specialized_algorithms/swap_cxx17.cc:
	Likewise.
	* testsuite/23_containers/deque/cons/deduction.cc: Likewise.
	* testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/forward_list/cons/deduction.cc:
	Likewise.
	* testsuite/23_containers/forward_list/modifiers/emplace_cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/list/cons/deduction.cc: Likewise.
	* testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/map/cons/deduction.cc: Likewise.
	* testsuite/23_containers/map/modifiers/extract.cc: Likewise.
	* testsuite/23_containers/map/modifiers/insert/83226.cc:
	Likewise.
	* testsuite/23_containers/map/modifiers/insert_or_assign/1.cc:
	Likewise.
	* testsuite/23_containers/map/modifiers/merge.cc: Likewise.
	* testsuite/23_containers/map/modifiers/try_emplace/1.cc:
	Likewise.
	* testsuite/23_containers/multimap/cons/deduction.cc: Likewise.
	* testsuite/23_containers/multimap/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/multimap/modifiers/merge.cc: Likewise.
	* testsuite/23_containers/multiset/cons/deduction.cc: Likewise.
	* testsuite/23_containers/multiset/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/multiset/modifiers/merge.cc: Likewise.
	* testsuite/23_containers/priority_queue/deduction.cc: Likewise.
	* testsuite/23_containers/queue/deduction.cc: Likewise.
	* testsuite/23_containers/queue/members/emplace_cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/set/cons/deduction.cc: Likewise.
	* testsuite/23_containers/set/modifiers/extract.cc: Likewise.
	* testsuite/23_containers/set/modifiers/merge.cc: Likewise.
	* testsuite/23_containers/set/modifiers/node_swap.cc: Likewise.
	* testsuite/23_containers/stack/deduction.cc: Likewise.
	* testsuite/23_containers/stack/members/emplace_cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/unordered_map/cons/deduction.cc:
	Likewise.
	* testsuite/23_containers/unordered_map/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/unordered_map/modifiers/insert_or_assign.cc:
	Likewise.
	* testsuite/23_containers/unordered_map/modifiers/merge.cc:
	Likewise.
	* testsuite/23_containers/unordered_map/modifiers/try_emplace.cc:
	Likewise.
	* testsuite/23_containers/unordered_multimap/cons/deduction.cc:
	Likewise.
	* testsuite/23_containers/unordered_multimap/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/unordered_multimap/modifiers/merge.cc:
	Likewise.
	* testsuite/23_containers/unordered_multiset/cons/deduction.cc:
	Likewise.
	* testsuite/23_containers/unordered_multiset/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/unordered_multiset/modifiers/merge.cc:
	Likewise.
	* testsuite/23_containers/unordered_set/cons/deduction.cc:
	Likewise.
	* testsuite/23_containers/unordered_set/modifiers/extract.cc:
	Likewise.
	* testsuite/23_containers/unordered_set/modifiers/merge.cc:
	Likewise.
	* testsuite/23_containers/vector/bool/emplace_cxx17_return.cc:
	Likewise.
	* testsuite/23_containers/vector/cons/89164_c++17.cc: Likewise.
	* testsuite/23_containers/vector/cons/deduction.cc: Likewise.
	* testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc:
	Likewise.