Suricata

Seems like using Option for `*const i8` is not FFI safe and Rust warns about it.
Using a null string in place of default port does seem to do the work though. Changed it in DCERPC only for now where there is not a fixed port of communication.
PR for review: https://github.com/OISF/suricata/pull/6234

Closed by PR: https://github.com/OISF/suricata/pull/6350