Fix tests that fail with -std=gnu++98 or -std=gnu++11

Fix tests that fail with -std=gnu++98 or -std=gnu++11

	* testsuite/18_support/set_terminate.cc: Do not run for C++98 mode.
	* testsuite/18_support/set_unexpected.cc: Likewise.
	* testsuite/20_util/is_nothrow_invocable/value.cc: Test converting to
	void.
	* testsuite/20_util/is_nothrow_invocable/value_ext.cc: Fix constexpr
	function to be valid in C++11.
	* testsuite/26_numerics/complex/proj.cc: Do not run for C++98 mode.
	* testsuite/experimental/names.cc: Do not run for C++98 mode. Do not
	include Library Fundamentals or Networking headers in C++11 mode.
	* testsuite/ext/char8_t/atomic-1.cc: Do not run for C++98 mode.

From-SVN: r271999