Function libsystemd_sys::bus::sd_bus_call_async

pub unsafe extern "C" fn sd_bus_call_async(
    bus: *mut sd_bus, 
    slot: *mut *mut sd_bus_slot, 
    m: *mut sd_bus_message, 
    callback: sd_bus_message_handler_t, 
    userdata: *mut c_void, 
    usec: u64
) -> c_int