added JSON UPDATE and DELETE tests

localtests/json57dml/create.sql

@@ -0,0 +1,27 @@
+drop table if exists gh_ost_test;
+create table gh_ost_test (
+  id int auto_increment,
+  i int not null,
+  updated tinyint not null default 0,
+  j json,
+  primary key(id)
+) auto_increment=1;
+
+drop event if exists gh_ost_test;
+delimiter ;;
+create event gh_ost_test
+  on schedule every 1 second
+  starts current_timestamp
+  ends current_timestamp + interval 60 second
+  on completion not preserve
+  enable
+  do
+begin
+  insert into gh_ost_test (id, i, j) values (null, 11, '"sometext"');
+  insert into gh_ost_test (id, i, j) values (null, 13, '{"key":"val"}');
+  insert into gh_ost_test (id, i, j) values (null, 17, '{"is-it": true, "count": 3, "elements": []}');
+
+  update gh_ost_test set j = '{"updated": 11}', updated = 1 where i = 11 and updated = 0;
+  update gh_ost_test set j = json_set(j, '$.count', 13), updated = 1 where i = 13 and updated = 0;
+  delete from gh_ost_test where i = 17;
+end ;;