*nix: SerialPortEngine, setCustomRate(), for another (any) *nix fixed warning about "unused parameter "rate".
*nix: SerialPortEngine, setCustomRate(), for another (any) *nix fixed
warning about "unused parameter "rate".

RoadWorksSoftware/QtSerialPort-OS2,RoadWorksSoftware/QtSerialPort-OS2,kobolabs/qtserialport,kobolabs/qtserialport