Function usrsctp_sys::usrsctp_set_upcall

pub unsafe extern "C" fn usrsctp_set_upcall(
    so: *mut socket, 
    upcall: Option<unsafe extern "C" fn(arg1: *mut socket, arg2: *mut c_void, arg3: c_int)>, 
    arg: *mut c_void
) -> c_int