[cond-optab] Convert mips

[Paolo Bonzini]

>> -      op0 = cmp_operands[1];
>> -      op1 = cmp_operands[0];
>> +      op0 = XEXP (comparison, 0);
>> +      op1 = XEXP (comparison, 1);

Argh, I screwed up my "smoke test". I'm about to advertise a
cond-optab svn branch, I'll make sure I fix this before creating it.

Paolo