* doc/xml/manual/status_cxx2017.xml: Update status.
	* doc/html/*: Regenerate.
	* include/std/type_traits (has_unique_object_representations): Guard
	with __has_builtin check.
	* libsupc++/new (launder): Define for C++17.
	* testsuite/18_support/launder/1.cc: New test.
	* testsuite/18_support/launder/requirements.cc: New test.
	* testsuite/18_support/launder/requirements_neg.cc: New test.

From-SVN: r241648