Add a special input configuration dialog for the GameCube Mic

This is more logical as the mic is plugged into an EXI slot so it should be configured via the GameCube config dialog.  This also allows to pass the right port number for the new dialog.

Source/Core/DolphinWX/Config/GameCubeConfigPane.h

@@ -34,6 +34,7 @@ private:
   void OnSlotBButtonClick(wxCommandEvent&);
 
   void ChooseEXIDevice(const wxString& device_name, int device_id);
+  void HandleEXISlotChange(int slot, const wxString& title);
   void ChooseSlotPath(bool is_slot_a, TEXIDevices device_type);
 
   wxArrayString m_ipl_language_strings;