Fix for bug #53238 "mdl_sync fails sporadically".

The problem was that mdl_sync.test was failing sporadically,
due to fact that part of the test didn't take into account
effects of MyISAM's concurrent insert.

This patch solves the problem by making test case robust
against concurrent insert.

mysql-test/r/mdl_sync.result

@@ -330,9 +330,9 @@ select column_name from information_schema.columns where
 table_schema='test' and table_name='t1';
 column_name
 c1
-select count(*) from t1;
-count(*)
-4
+# Disable result log to make test robust against
+# effects of concurrent insert.
+select * from t1;
 insert into t1 values (1);
 # Check that SNW lock is not compatible with SW lock.
 # Again we use ALTER TABLE which fails after opening

mysql-test/t/mdl_sync.test

@@ -462,7 +462,11 @@ handler t1 open;
 handler t1 close;
 select column_name from information_schema.columns where
   table_schema='test' and table_name='t1';
-select count(*) from t1;
+--echo # Disable result log to make test robust against
+--echo # effects of concurrent insert.
+--disable_result_log
+select * from t1;
+--enable_result_log
 insert into t1 values (1);
 --echo # Check that SNW lock is not compatible with SW lock.
 --echo # Again we use ALTER TABLE which fails after opening