regression in Newlib 4.2.0

[Paul Zimmermann]

       Hi,

I noticed a regression in Newlib 4.2.0:

Checking exp with newlib-4.2.0.20211231
MPFR library: 4.1.0
MPFR header:  4.1.0 (based on 4.1.0)
libm wrong by up to 1.94e+04 ulp(s) for x=0x1.62e302p+6
exp      gives inf
mpfr_exp gives 0x1.ff691ep+127
Total: errors=17982998 (0.42%) errors2=151 maxerr=1.94e+04 ulp(s)

The largest error for expf in Newlib 4.1.0 was 0.911 ulps
(https://members.loria.fr/PZimmermann/papers/accuracy.pdf).

Best regards,
Paul