Since e6b332aa, we have proper support for detecting client/server direction. So Tinc dissector is now able to properly initialize the cache entry only when needed and not anymore at the SYN time; initializing that entry for **every** SYN packets was a complete waste of resources. Since 4896dabb, the various `struct ndpi_call_function_struct` structures are not more separate objects and therefore comparing them using only their pointers is bogus: this bug was triggered by this change because `ndpi_str->callback_buffer_size_tcp_no_payload` is now 0.