[Bug target/95531] Failure to use TZCNT for __builtin_ffs

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95531

--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> ---
What is the question?  4+4 = 16?  Not all costs are included in
that "4+4" :-)  It does look weird; patches welcome.