[Bug libstdc++/108836] std::mutex disappears in single-threaded libstdc++ builds

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108836

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
mingw32 is no longer defaults to a single threaded and std::mutex is supported
there on the trunk for GCC 13 ....