[Bug c++/120720] __builtin_rev_crc32_data8 (and family) should be constexpr functions

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120720

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
You could always use the non builtin constexpr function to do the same for
constexpr part like is required for strlen, etc.