Fixed that Truncate_versioning_privilege works as any other privilege
during upgrade:

- If the privilege field does not exists, add it to the user and db tables.
  If the user had super_privilege then the user will also get the new
  Truncate_versioning_privilege.

This is done to ensure that if one has GRANT ALL PRIVILEGE before, one
will continue to have it after running mysql_upgrade.

This also fixes a bug where the Truncate_versioning_privilege