Update.

Update.

	* internals.h: Declare __pthread_max_stacksize.
	* pthread.c (__pthread_max_stacksize): New variable.
	(__pthread_initialize_manager): Determine __pthread_initialize_manager
	value.
	* manager.c (thread_segment): Return always NULL if FLOATING_STACKS.
	(pthread_allocate_stack): Allow kernel to choose stack address if
	FLOATING_STACKS.  This also handles variable-sized stacks.
	Always allocate stack and guardoage together.  Use mprotect to
	change guardpage access.
	* sysdeps/i386/useldt.h: Define FLOATING_STACKS and
	ARCH_STACK_MAX_SIZE.

	* attr.c (__pthread_attr_setstacksize): Also test value against
	upper limit.