mysql57 test: disable meaningless test

Because "DELAYED" is ignored in MySQL 5.7.

mysql-test/mroonga/storage/insert/t/delayed.test

@@ -1,4 +1,4 @@
-# Copyright(C) 2014 Kouhei Sutou <kou@clear-code.com>
+# Copyright(C) 2014-2016 Kouhei Sutou <kou@clear-code.com>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -15,6 +15,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 --source include/not_embedded.inc
+--source ../../../include/mroonga/skip_mysql_57_or_later.inc
 --source ../../../include/mroonga/have_mroonga.inc
 
 --disable_warnings