Bug#36035 I_S.TABLES.UPDATE_TIME not being set on INSERT for Windows

added FLUSH TABLES after INSERT because UPDATE_TIME is updated with delay
on Win.

mysql-test/suite/funcs_1/datadict/is_tables.inc

@@ -346,6 +346,7 @@ WHERE table_name = 't1_my_tablex';
 #   Enforce a time difference bigger than the smallest unit (1 second).
 --real_sleep 1.1
 INSERT INTO db_datadict.t1_my_tablex SET f1 = 3;
+FLUSH TABLES;
 SELECT UPDATE_TIME > @UPDATE_TIME
     AS "Is current UPDATE_TIME bigger than before last INSERT?"
 FROM information_schema.tables

mysql-test/suite/funcs_1/r/is_tables.result

@@ -310,6 +310,7 @@ SELECT UPDATE_TIME, checksum INTO @UPDATE_TIME, @checksum
 FROM information_schema.tables
 WHERE table_name = 't1_my_tablex';
 INSERT INTO db_datadict.t1_my_tablex SET f1 = 3;
+FLUSH TABLES;
 SELECT UPDATE_TIME > @UPDATE_TIME
 AS "Is current UPDATE_TIME bigger than before last INSERT?"
 FROM information_schema.tables