[PATCH] ntdll: Decouple pthread stack and win32 stack.

[Jefferson Carpenter]

Is there any particular reason to place the pthread stack adjacent to 
the win32 stack?  If the pthread stack happened to extend past 
PTHREAD_STACK_MIN while the win32 thread was started, writes to the 
win32 stack (such as the initial CONTEXT) would overwrite the pthread stack.

-Jefferson