* include/std/shared_mutex: Implement N3659.
	* include/bits/c++14_warning.h: New.
	* include/Makefile.am: Add new headers.
	* include/Makefile.in: Regenerate.
	* testsuite/30_threads/shared_lock/cons/1.cc: New.
	* testsuite/30_threads/shared_lock/locking/2.cc: New.
	* testsuite/30_threads/shared_lock/cons/2.cc: New.
	* testsuite/30_threads/shared_lock/locking/3.cc: New.
	* testsuite/30_threads/shared_lock/cons/3.cc: New.
	* testsuite/30_threads/shared_lock/locking/4.cc: New.
	* testsuite/30_threads/shared_lock/cons/4.cc: New.
	* testsuite/30_threads/shared_lock/modifiers/1.cc: New.
	* testsuite/30_threads/shared_lock/cons/5.cc: New.
	* testsuite/30_threads/shared_lock/modifiers/2.cc: New.
	* testsuite/30_threads/shared_lock/cons/6.cc: New.
	* testsuite/30_threads/shared_lock/requirements/
	explicit_instantiation.cc: New.
	* testsuite/30_threads/shared_lock/locking/1.cc: New.
	* testsuite/30_threads/shared_lock/requirements/typedefs.cc: New.
	* testsuite/30_threads/shared_mutex/cons/1.cc: New.
	* testsuite/30_threads/shared_mutex/cons/assign_neg.cc: New.
	* testsuite/30_threads/shared_mutex/cons/copy_neg.cc: New.
	* testsuite/30_threads/shared_mutex/requirements/
	standard_layout.cc: New.
	* testsuite/30_threads/shared_mutex/try_lock/1.cc: New.
	* testsuite/30_threads/shared_mutex/try_lock/2.cc: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@200134 138bc75d-0d04-0410-961f-82ee72b054a4