[Bug c/124699] [13 Regression] Expression using __builtin_ffsll() may not be considered constant

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124699

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I am not sure if r14-4592-g0d00385eaf72cc is a fix or just works around the
issue.