https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86535
--- Comment #17 from Piotr Kubaj <pkubaj at anongoth dot pl> ---
Since you mentioned libgo/runtime_sysinfo.go, I also had a look there and saw
that umtx_time is already present there:
type __umtx_time struct { _timeout timespec; _flags uint32; _clockid uint32; }
const _sizeof__umtx_time = 24
