ZLIB_ERROR_CODE   936 contrib/tools/pngfix.c       case ZLIB_ERROR_CODE:       return "zlib";
ZLIB_ERROR_CODE   958 contrib/tools/pngfix.c       case ZLIB_ERROR_CODE:       reason = "zlib error:"; break;
ZLIB_ERROR_CODE  2004 contrib/tools/pngfix.c       stop(file, ZLIB_ERROR_CODE, "could not uncompress IDAT");