[Bug tree-optimization/90838] Detect table-based ctz implementation

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90838

--- Comment #20 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
No, because __builtin_ctz is branchless too, it just has UB when the argument
is 0.