[glibc] powerpc: Update acosf ulps

[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.

Paul