Bug #39958: Test "windows" lacks a cleanup

Added the missing DROP TABLE

mysql-test/r/windows.result

@@ -18,4 +18,5 @@ EXPLAIN SELECT * FROM t1 WHERE b =  (SELECT max(2));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+DROP TABLE t1;
 End of 5.0 tests.

mysql-test/t/windows.test

@@ -33,5 +33,6 @@ drop table t1;
 #
 CREATE TABLE t1 (a int, b int); INSERT INTO t1 VALUES (1,1);
 EXPLAIN SELECT * FROM t1 WHERE b =  (SELECT max(2));
+DROP TABLE t1;
 
 --echo End of 5.0 tests.