Make use of extensions more explicit in libstdc++ tests

Make use of extensions more explicit in libstdc++ tests

	* testsuite/18_support/bad_exception/23591_thread-1.c: Add
	-Wno-pedantic to dg-options.
	* testsuite/20_util/align/2.cc: Use type as operand of alignof.
	* testsuite/20_util/is_floating_point/value.cc: Add -Wno-pedantic
	to dg-options.
	* testsuite/20_util/specialized_algorithms/uninitialized_fill/32158.cc:
	Remove extra semi-colon.
	* testsuite/23_containers/array/tuple_interface/tuple_element.cc:
	Always supply second argument to static_assert.
	* testsuite/25_algorithms/lower_bound/no_operator_ne.cc: Remove extra
	semi-colon.
	* testsuite/26_numerics/complex/c99.cc: Add -Wno-pedantic to
	dg-options.
	* testsuite/26_numerics/complex/literals/values.cc: Likewise.
	* testsuite/29_atomics/atomic/60695.cc: Likewise.
	* testsuite/29_atomics/atomic/62259.cc: use __alignof__ instead of
	alignof when operand is an object not a type.
	* testsuite/decimal/ctor.cc: Add -Wno-pedantic to dg-options.
	* testsuite/decimal/make-decimal.cc: Likewise.
	* testsuite/experimental/type_traits/value.cc: Always supply second
	argument to static_assert.
	* testsuite/util/testsuite_common_types.h: Use __extension__ for
	__int128 types.

From-SVN: r235154