[PATCH 07/12] benchtests: Add coshf function to bench-math

[Paul Zimmermann]

       Dear Sunil,

many entries (for example 0x1.631844p+9) yield a cosh value larger than 2^128
thus an overflow, and are not very representative of real applications.

Except maybe a few values such that cosh(x) is near 2^128, it would be better
to have cosh(x) < 2^128.

Paul