[PATCH, rs6000] Predefine __PPU__ to indicate -mcpu=cell

[David Edelsohn]

>>>>> Ulrich Weigand writes:

Ulrich> I see, it seems I have misinterpreted existing code like
Ulrich> if (rs6000_cpu == PROCESSOR_PPC405)
Ulrich> builtin_define ("__PPC405__");

Ulrich> David, do you have any suggestions how to properly check for -mcpu=cell?
Ulrich> It seems this information is not actually available anywhere ...

	No, it's not available, which is why we use rs6000_cpu as the best
available option.  The other option would be a new instruction that is
specific to Cell PPU, but that does not exist.

	Most users do not mix-and-match as Andrew warns.

David