Update test results.

mysql-test/suite/pbxt/r/negation_elimination.result

@@ -321,7 +321,7 @@ select * from t1 where not(NULL or a);
 a
 explain select * from t1 where not(NULL and a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	a	a	5	const	1	Using where; Using index
+1	SIMPLE	t1	ref	a	a	5	const	1	Using index
 select * from t1 where not(NULL and a);
 a
 0