semun
union semun semarg;
buf = va_arg(ap, union semun).buf64;
arg = (uintptr_t)va_arg(ap, union semun).val;
arg = (uintptr_t)va_arg(ap, union semun).array;
arg = (uintptr_t)va_arg(ap, union semun).buf;
union semun sem_union;
union semun sem_union;