Fix for broken build (::None)

None clashed with something else under linux, probably a macro expansion.

src/export/ExportCL.cpp

@@ -24,7 +24,7 @@
 #include <wx/process.h>
 #include <wx/sizer.h>
 #include <wx/textctrl.h>
-#include "FileNames.h"
+#include "../FileNames.h"
 #include "Export.h"
 
 #include "../Mix.h"

src/export/ExportMP3.cpp

@@ -660,7 +660,7 @@ public:
        * "Where would I find the file %s" instead if you want. */
       question.Printf(_("Where is %s?"), mName.c_str());
 
-      wxString path = FileNames::SelectFile(FileNames::Operation::None,
+      wxString path = FileNames::SelectFile(FileNames::Operation::_None,
                                    question,
                                    mLibPath.GetPath(),
                                    mLibPath.GetName(),