3.4 PATCH: Consistently use _ABIO32 for _MIPS_SIM

[Rainer Orth]

Eric Christopher writes:

> I'm worried about current users. Anything use it in, say, the linux
> kernel after including sgidefs?

There's no change here: with <sgidefs.h> included, _MIPS_SIM_ABI32 and
_ABIO32 are identical (1), so _MIPS_SIM has the same value before and after
my patch.

There's only a change when someone used _MIPS_SIM *without <sgidefs.h>* and
relied on the fact that _MIPS_SIM was 0 (a value not matching any defined
_MIPS_SIM_ABI*/_ABI* value) in this case.  As Alexandre agreed, this use
was broken from the beginning and I don't think we should support this.

	Rainer