Function SetupDiGetClassDevsA 

pub unsafe fn SetupDiGetClassDevsA<P1>(
    classguid: Option<*const GUID>,
    enumerator: P1,
    hwndparent: Option<HWND>,
    flags: SETUP_DI_GET_CLASS_DEVS_FLAGS,
) -> Result<HDEVINFO>
where
    P1: Param<PCSTR>,