Extended test case to check that binary column

actually adds zeroes, not spaces at the end.

mysql-test/r/alter_table.result

@@ -636,7 +636,13 @@ INSERT INTO t1 VALUES ('test');
 SELECT LENGTH(s) FROM t1;
 LENGTH(s)
 8
+SELECT HEX(s) FROM t1;
+HEX(s)
+7465737400000000
 ALTER TABLE t1 MODIFY s BINARY(10);
+SELECT HEX(s) FROM t1;
+HEX(s)
+74657374000000000000
 SELECT LENGTH(s) FROM t1;
 LENGTH(s)
 10