Effects of newly introduced -mpcX 80387 precision flag

[Uros Bizjak]

Bradley Lucier wrote:

>> What about "significant loss of accuracy" as these options probably 
>> won't cause a nuclear reactor meltdown ;)
>
> Well, I did some googling, and the technical term I was thinking of 
> was "catastrophic cancellation".  So how about
>
> Note that some mathematical routines in such libraries could suffer 
> significant loss of accuracy, typically through so-called 
> "catastrophic cancellation", when this option is used to set the 
> precision to less than extended precision.

I think this is OK. So if nobody objects, this patch is OK for mainline.

Thanks,
Uros.