Function sd_event_add_time 

pub unsafe extern "C" fn sd_event_add_time(
    e: *mut sd_event,
    s: *mut *mut sd_event_source,
    clock: clockid_t,
    usec: u64,
    accuracy: u64,
    callback: sd_event_time_handler_t,
    userdata: *mut c_void,
) -> c_int