* child_info.h (CURR_CHILD_INFO_MAGIC): Update.

(class child_info_fork): Remove stacksize, add stackaddr and guardsize
	members.
	* dcrt0.cc (child_info_fork::alloc_stack_hard_way): Partial rewrite
	to regenerate the stack exactly as in the parent.
	(child_info_fork::alloc_stack): Set stackaddr to 0, rather than
	stacksize.
	(dll_crt0_1): Check for stackaddr before changing the stack addresses
	in the TEB.
	* fork.cc (frok::child): Check for stackaddr here.
	(frok::parent): Set ch.stackaddr and ch.guardsize if not called from
	the main thread.
	* init.cc (dll_entry): Replace pointer to NT_TIB with pointer to TEB.
	Fix incorrectly changed address test before removing _my_tls.
	Set StackLimit to NULL on Windows 2000.  Explain why.
	* miscfuncs.cc (struct thread_wrapper_arg): Store stackbase rather
	than stacksize, store commitaddr, remove guardsize.  Store all pointers
	as char * for easier address arithmetic.
	(thread_wrapper): Rewrite to remove OS stack before calling thread
	function.  Add lots of comments to explain what we do.
	(CygwinCreateThread): Reserve our own stack in case we got no
	application stack.  Add comments.
	* ntdll.h (struct _TEB): Extend defintion up to DeallocationStack
	member.
	* thread.cc (pthread_attr::pthread_attr): Use "(size_t) -1"
	rather then 0xffffffff.
	* wincap.h (wincaps::has_stack_size_param_is_a_reservation): New
	element.
	* wincap.cc: Implement above element throughout.

winsup/cygwin/wincap.h

@@ -41,6 +41,7 @@ struct wincaps
   unsigned has_fast_cwd					: 1;
   unsigned has_restricted_raw_disk_access		: 1;
   unsigned use_dont_resolve_hack			: 1;
+  unsigned has_stack_size_param_is_a_reservation	: 1;
 };
 
 class wincapc
@@ -90,6 +91,7 @@ public:
   bool	IMPLEMENT (has_fast_cwd)
   bool	IMPLEMENT (has_restricted_raw_disk_access)
   bool	IMPLEMENT (use_dont_resolve_hack)
+  bool	IMPLEMENT (has_stack_size_param_is_a_reservation)
 
 #undef IMPLEMENT
 };