[Exp PyROOT] Silence cast-function-type warning (gcc8)

bindings/pyroot_experimental/PyROOT/src/RPyROOTApplication.cxx

@@ -211,7 +211,9 @@ static int EventInputHook()
 
 ////////////////////////////////////////////////////////////////////////////
 /// \brief Install a method hook for sending events to the GUI.
-PyObject *PyROOT::RPyROOTApplication::InstallGUIEventInputHook()
+/// \param[in] self Always null, since this is a module function.
+/// \param[in] args Pointer to an empty Python tuple.
+PyObject *PyROOT::RPyROOTApplication::InstallGUIEventInputHook(PyObject * /* self */, PyObject * /* args */)
 {
    if (PyOS_InputHook && PyOS_InputHook != &EventInputHook)
       sOldInputHook = PyOS_InputHook;

bindings/pyroot_experimental/PyROOT/src/RPyROOTApplication.h

@@ -31,7 +31,7 @@ namespace PyROOT {
 class RPyROOTApplication : public TApplication {
 public:
    static PyObject *InitApplication(PyObject *self, PyObject *args);
-   static PyObject *InstallGUIEventInputHook();
+   static PyObject *InstallGUIEventInputHook(PyObject *self, PyObject *args);
 
    RPyROOTApplication(const char *acn, int *argc, char **argv);
    virtual ~RPyROOTApplication() {}