faster expf128

[Paul Zimmermann]

       Hi,

I have written some expf128 for x86_64 that is more than 10 times faster than
the current glibc/libquadmath code [1] (see slide 21 of [2]).

Before making a proper patch for glibc, I'd like to make sure it fits the
glibc requirements. In particular, the table size is 16kb. Is that ok?
If too large, what table size would be ok?

Best regards,
Paul

[1] https://homepages.loria.fr/PZimmermann/glibc-contrib/
[2] https://members.loria.fr/PZimmermann/talks/quad.pdf