[glibc] powerpc: Update acosf ulps

[Florian Weimer]

* Paul Zimmermann:

>        Hi Florian,
>
>> Isn't the new acosf implementation supposed to be correctly rounded?
>
> yes, but due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57245,
> the new implementation might be miscompiled by gcc < 12.
>
> I strongly recommend updating ulps only with gcc >= 12.

Oh, I wasn't aware of that.  I think I pushed quite a few ulps updates
that were caused by this bug. 8-(

I'll ask if we can get our build of GCC 11 fixed.  Maybe we should raise
the minimum version to GCC 12 for glibc builds if earlier versions
cannot build libm correctly.

Thanks,
Florian