* cygwin.din (pthread_attr_getguardsize): Export.

	* cygwin.din (pthread_attr_getguardsize): Export.
	(pthread_attr_setguardsize): Export.
	(pthread_attr_setstack): Export.
	(pthread_attr_setstackaddr): Export.
	* init.cc (dll_entry): Remove wow64_test_stack_marker.  Check for
	unusual stack address by testing stack addresses from current TEB.
	Check validity of _my_tls by testing if it's within the stack as
	given in current TEB.
	* miscfuncs.cc (struct thread_wrapper_arg): New structure used to
	push all required information to thread_wrapper function.
	(thread_wrapper): Wrapper function for actual thread function.
	If an application stack has been given, change %ebp and %esp so that
	the thread function runs on that stack.  If the thread has been created
	by CygwinCreateThread, set up the POSIX guard pages if necessary.
	(CygwinCreateThread): New function.
	* miscfuncs.h (CygwinCreateThread): Declare.
	* ntdll.h (struct _TEB): Define all members up to Peb.
	* posix.sgml (std-susv4): Move pthread_attr_getguardsize,
	pthread_attr_setguardsize and pthread_attr_setstack here.
	(std-deprec): Add pthread_attr_setstackaddr.
	* sysconf.cc (sca): Set _SC_THREAD_ATTR_STACKADDR to
	_POSIX_THREAD_ATTR_STACKADDR.
	* thread.cc (pthread::precreate): Copy pthread_attr stackaddr and
	guardsize members.
	(pthread::create): Call CygwinCreateThread.
	(pthread_attr::pthread_attr): Initialize guardsize.
	(pthread_attr_setstack): New function.
	(pthread_attr_setstackaddr): New function.
	(pthread_attr_setguardsize): New function.
	(pthread_attr_getguardsize): New function.
	(pthread_getattr_np): Copy attr.guardsize.
	* thread.h (pthread_attr): Add member guardsize.
	* include/pthread.h (pthread_attr_getguardsize): Declare.
	(pthread_attr_setguardsize): Declare.
	* include/cygwin/version.h: Bump API minor number.