https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63287
--- Comment #7 from Alisdair Meredith <alisdairm at me dot com> --- Late comment: according to [intro.multithread.general] it is a requirement for hosted implementations to support more than one thread of execution, but implementation defined for a free-standing implementation. I am not sure if that has a bearing on the affected platforms.
