[Bug libstdc++/66146] call_once not C++11-compliant on ppc64le

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66146

--- Comment #54 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Because it would be an ABI break. It's a good option if backwards compatibility
is not required, I've suggested it before.