[Bug libstdc++/111639] HAVE_ACOSF etc. are wrong on avr

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111639

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
So then we do need to fix the autoconf macros.