Main: Move unofficial build check to its own function

Removes the need to explicitly call exit.

Source/Core/DolphinWX/Main.h

@@ -32,6 +32,7 @@ private:
 	void OnEndSession(wxCloseEvent& event);
 	void InitLanguageSupport();
 	void AfterInit();
+	static bool DolphinEmulatorDotComTextFileExists();
 
 	bool m_batch_mode = false;
 	bool m_load_file = false;