Move IOFile to a separate file

Reduces the number of files that need to be recompiled
when making changes to FileUtil.h.

Source/Core/DolphinWX/NetPlay/NetPlayLauncher.cpp

@@ -5,7 +5,6 @@
 #include <wx/gdicmn.h>
 
 #include "Common/CommonTypes.h"
-#include "Common/FileUtil.h"
 #include "Common/IniFile.h"
 #include "Common/StringUtil.h"
 #include "DolphinWX/NetPlay/NetPlayLauncher.h"