r199367 - MachO: use *-*-*-macho for MachO embedded targets.

[Tim Northover]

>> +// CHECK-NOT: #define __MACH__
>
> This seems wrong/odd. You've got something that is "mach-o" and yet doesn't
> define Mach?

Hmm, I see. I'd taken that as referring to the kernel rather than the
object format. But I see that there isn't actually a __MACHO__ define
so the two concepts are probably conflated at the moment.

I'd prefer to fix that by defining __MACHO__ for both rather than
defining __MACH__ on embedded targets.

Cheers.

Tim.