Submitted by: @mrotteveel

A normal user without the ALTER ANY ROLE privilege is allowed to put comments on roles.

```
create user testuser password 'testuser';
commit;
connect '<db>' user testuser password 'testuser';
comment on role rdb$admin is 'unprivileged comment';
commit;
```

The comment is added on role RDB$ADMIN without error, expected behaviour is an error with a message like:

"""
Statement failed, SQLSTATE = 28000
unsuccessful metadata update
-COMMENT ON XYZ failed
-no permission for ALTER access to ROLE RDB$ADMIN
-Effective user is TESTUSER
"""

Commits: 04598a6 3f2e1ea