var-tracking wrt. leaf regs on sparc

[Eric Botcazou]

> Yes, this works perfectly, Jakub any objections?
> 
> gcc/
> 
> 2013-02-06  David S. Miller  <davem@davemloft.net>
> 
> 	* var-tracking.c (vt_add_function_parameter): Test the presence of
> 	HAVE_window_save properly and do not remap argument registers when
> 	we have a leaf function.

Please put it on the 4.7 branch as well if approved, this worked (by chance) 
before my change.  TIA.

-- 
Eric Botcazou