Function gcoap_req_send

unsafe extern "C" fn gcoap_req_send(
    buf: *const uint8_t,
    len: size_t,
    remote: *const sock_udp_ep_t,
    local: *const sock_udp_ep_t,
    resp_handler: gcoap_resp_handler_t,
    context: *mut c_void,
    tl_type: gcoap_socket_type_t,
) -> ssize_t