udp multicast send can't use specified local ip address

[kkzi]

code from examples/udp_multicast/main.cpp
it can't bind local ip address

kissnet::udp_socket mcast_send_socket(kissnet::endpoint(global_mcast_addr, global_mcast_port));
while (global_thread_running) {
    //Send the payload
    auto[sent_bytes, status] = mcast_send_socket.send(send_this, sizeof(send_this));
    if (sent_bytes != sizeof(send_this) || status != kissnet::socket_status::valid) {
        std::cout << "kissnet multicast send failure" << std::endl;
        break;
    }
    std::cout << "Sent multicast packet." << std::endl;

    //Wait for 100 milliseconds
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
}

maybe we could do this to support binding local ip address

kissnet::endpoint remote { global_mcast_addr, global_mcast_port };
kissnet::udp_socket mcast_send_socket(kissnet::endpoint { "192.168.1.110", 0 });
mcast_send_socket.bind();
while (1)
{
    //Send the payload
    auto [sent_bytes, status] = mcast_send_socket.send(frame, remote);
    std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}