[Bug c/123987] isinfl isinff incorrectly for x86 and arm64

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123987

--- Comment #10 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
additionally, gcc provides __builtin_isinf_sign() &c.  I suspect that if gcc
wants the compiler to respect its extended semantics for isinf, then its
headers should arrange for the function to be remapped accordingly.

But that makes this a glibc bug.