* dcrt0.cc (child_info_fork::alloc_stack_hard_way): Check if the

requested stack is application-provided within the user heap or an
	mmapped region.  If so, just use it.  Add comment to explain why.
	* miscfuncs.cc (thread_wrapper): If an application-provided stack
	has been given, implement cygtls area at the stackbase.  Fix comment.
	* mmap.cc (is_mmapped_region): New function.
	* winsup.h (is_mmapped_region): Declare.

winsup/cygwin/winsup.h

@@ -270,6 +270,7 @@ enum mmap_region_status
     MMAP_NORESERVE_COMMITED
   };
 mmap_region_status mmap_is_attached_or_noreserve (void *addr, size_t len);
+bool is_mmapped_region (caddr_t start_addr, caddr_t end_address);
 
 inline bool flush_file_buffers (HANDLE h)
 {