message: Use 8.3 filenames in FixDuplicateItems() too
  Harden gettext invocation in POCatalog::FixDuplicateItems() against
  codepage, whitespace etc. issues using CliSafeFileName() as is done
  in other places.
  Fixes
diff: @@ -1606,8 +1606,8 @@ bool POCatalog::FixDuplicateItems()
  }
  ExecuteGettext(wxString::Format("msguniq -o %s %s",
  - QuoteCmdlineArg(po_file_fixed),
  - QuoteCmdlineArg(po_file_temp)));
  + QuoteCmdlineArg(CliSafeFileName(po_file_fixed)),
  + QuoteCmdlineArg(CliSafeFileName(po_file_temp))));
  if (!wxFileName::FileExists(po_file_fixed))
  return false;
  