* cygwin.din (pthread_spin_destroy): Export.

	* cygwin.din (pthread_spin_destroy): Export.
	(pthread_spin_init): Export.
	(pthread_spin_lock): Export.
	(pthread_spin_trylock): Export.
	(pthread_spin_unlock): Export.
	* posix.sgml (std-susv4): Add pthread_spin_destroy, pthread_spin_init,
	pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock.
	(std-notimpl): Remove pthread_spin_[...].
	* pthread.cc (pthread_spin_init): New function.
	* thread.cc (pthread_spinlock::is_good_object): New function.
	(pthread_mutex::pthread_mutex): Rearrange initializers to accommodate
	protected data in pthread_mutex.
	(pthread_spinlock::pthread_spinlock): New constructor.
	(pthread_spinlock::lock): New method.
	(pthread_spinlock::unlock): New method.
	(pthread_spinlock::init): New method.
	(pthread_spin_lock): New function.
	(pthread_spin_trylock): New function.
	(pthread_spin_unlock): New function.
	(pthread_spin_destroy): New function.
	* thread.h (PTHREAD_SPINLOCK_MAGIC): Define.
	(class pthread_mutex): Change access level of members shared with
	derived classes to protected.
	(pthread_mutex::set_shared): New protected method.
	(class pthread_spinlock): New class, derived class of pthread_mutex.
	* include/pthread.h (pthread_spin_destroy): Declare.
	(pthread_spin_init): Declare.
	(pthread_spin_lock): Declare.
	(pthread_spin_trylock): Declare.
	(pthread_spin_unlock): Declare.
	* include/cygwin/types.h (pthread_spinlock_t): New typedef.
	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.