_cv_mtx_timedwait
int _cv_mtx_timedwait(struct cv *, struct mtx *, int timo, int wakesig);
_cv_mtx_timedwait((cv), (mtx), 0, 0)
_cv_mtx_timedwait((cv), (mtx), 0, 1)
_cv_mtx_timedwait((cv), (mtx), (timeo), 0)
_cv_mtx_timedwait((cv), (mtx), (timeo), 1)