[Bug middle-end/123869] Negation of _Float16 should just flip the bit and not promote to _Float32

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123869

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
abs has the same issue.