Skip tests for GNU extensions when testing with strict mode

Skip tests for GNU extensions when testing with strict mode

Tests for the implicit allocator rebinding extension will fail if the
extension is disabled, so skip them.

	* testsuite/23_containers/array/requirements/explicit_instantiation/
	3.cc: Skip test when compiled with a -std=c++NN strict mode.
	* testsuite/23_containers/deque/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/forward_list/requirements/
	explicit_instantiation/3.cc: Likewise.
	* testsuite/23_containers/list/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/map/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/multimap/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/multiset/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/set/requirements/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/unordered_map/requirements/
	explicit_instantiation/3.cc: Likewise.
	* testsuite/23_containers/unordered_multimap/requirements/
	explicit_instantiation/3.cc: Likewise.
	* testsuite/23_containers/unordered_multiset/requirements/
	explicit_instantiation/3.cc: Likewise.
	* testsuite/23_containers/unordered_set/requirements/
	explicit_instantiation/3.cc: Likewise.
	* testsuite/23_containers/vector/ext_pointer/explicit_instantiation/
	3.cc: Likewise.
	* testsuite/23_containers/vector/requirements/explicit_instantiation/
	3.cc: Likewise.

From-SVN: r265334