[Bug target/59874] Missing builtin (__builtin_clzs) when compiling with g++

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59874

--- Comment #6 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Allan Jensen from comment #5)
> This is more problematic to fix in Qt itself. How can we determine if we
> should/can use __builtin_clzs or __lzcnt16?
> 
> Note the former is practically standard being supported by both older gcc
> and clang. There is also the problem that we need to call a builtin, because
> the C-intrinsics don't work as constexpr.

Well, if the change makes so much pain, let's put these intrinsics back.