[Bug libstdc++/112351] libstdc++ locale init doesn't handle __gthread_once failure

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112351

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah yes, that's a good point. Patrick's improvement affects this initialization.

It's not done for all targets though, as not all targets have linker support
for the init_priority attribute (notably, darwin doesn't).