Added system for handling core errors in citra-qt.

src/citra_qt/main.h

@@ -125,6 +125,7 @@ private slots:
     void OnDisplayTitleBars(bool);
     void ToggleWindowMode();
     void OnCreateGraphicsSurfaceViewer();
+    void OnCoreError(Core::System::ResultStatus);
 
 private:
     void UpdateStatusBar();