RFA: Fix tracking of pass-by-reference parameters

[Eric Botcazou]

[stretching a bit the purview of my maintainership...]

> 	* tree.h (set_decl_incoming_rtl): Add a by_reference_p parameter.
> 	* emit-rtl.c (set_decl_incoming_rtl): Likewise.  Don't set the
> 	rtl's register attributes when the parameter is true.
> 	* function.c (assign_parms_unsplit_complex, assign_parms)
> 	(expand_function_start): Update calls to set_decl_incoming_rtl.

OK, thanks.

-- 
Eric Botcazou