PR libstdc++/79433
	* doc/xml/manual/status_cxx2017.xml: Update feature-test macros.
	* doc/html/*: Regenerate.
	* include/Makefile.am: Remove <bits/c++17_warning.h>.
	* include/Makefile.in: Regenerate.
	* include/bits/c++17_warning.h: Remove.
	* include/bits/string_view.tcc: Do not include <bits/c++17_warning.h>
	for pre-C++17 modes.
	* include/std/any: Likewise.
	(__cpp_lib_any): Define.
	* include/std/mutex (__cpp_lib_scoped_lock): Adjust value as per new
	SD-6 draft.
	* include/std/numeric (__cpp_lib_gcd_lcm): Define as per new SD-6
	draft.
	* include/std/optional: Do not include <bits/c++17_warning.h>.
	(__cpp_lib_optional): Define.
	* include/std/shared_mutex: Do not include <bits/c++14_warning.h>.
	* include/std/string_view: Do not include <bits/c++17_warning.h>.
	(__cpp_lib_string_view): Define.
	* include/std/variant: Do not include <bits/c++17_warning.h>.
	(__cpp_lib_variant): Define.
	* testsuite/20_util/optional/cons/value_neg.cc: Adjust dg-error line
	numbers.
	* testsuite/26_numerics/gcd/1.cc: Test for __cpp_lib_gcd_lcm.
	* testsuite/26_numerics/gcd/gcd_neg.cc: Adjust dg-error line
	numbers.
	* testsuite/26_numerics/lcm/1.cc: Test for __cpp_lib_gcd_lcm.
	* testsuite/26_numerics/lcm/lcm_neg.cc: Adjust dg-error line
	numbers.
	* testsuite/30_threads/scoped_lock/requirements/typedefs.cc: Adjust
	expected value of __cpp_lib_scoped_lock.

From-SVN: r252018