a* can't be found, but a*a can

@tomatolog is already working on this.

Since Apr 19, 2024.

```sql
mysql> drop table if exists t; create table t(f text) charset_table='a,*'; insert into t values (1,'a'),(2,'a*'),(3,'a*a');

mysq> select * from t;
+------+------+
| id | f |
+------+------+
| 1 | a |
| 2 | a* |
| 3 | a*a |
+------+------+
3 rows in set (0.00 sec)

mysql> select * from t where match('a*'); +------+------+
| id | f |
+------+------+
| 1 | a |
+------+------+
1 row in set (0.00 sec)

mysql> select * from t where match('a*a');
+------+------+
| id | f |
+------+------+
| 3 | a*a |
+------+------+
1 row in set (0.00 sec)
```