cleanup: refactor grant table classes in sql_acl.cc

move all backward compatibility related code into User_table,
the caller should not know or care anymore.

Other tables (Db_table, etc) are *not* refactored.

For consistency with other updates, setting a default role
no longer errors out when the mysql.user table is too old.

mysql-test/suite/roles/create_and_drop_role_invalid_user_table.result

@@ -15,7 +15,6 @@ create role test_role;
 create user test_user@localhost;
 grant test_role to test_user@localhost;
 set default role test_role for root@localhost;
-ERROR HY000: Column count of mysql.user is wrong. Expected 46, found 45. Created with MariaDB MYSQL_VERSION_ID, now running MYSQL_VERSION_ID. Please use mysql_upgrade to fix this error
 drop role test_role;
 drop user test_user@localhost;
 alter table user add column default_role char(80) binary default '' not null

mysql-test/suite/roles/create_and_drop_role_invalid_user_table.test

@@ -29,8 +29,8 @@ after password_expired;
 create role test_role;
 create user test_user@localhost;
 grant test_role to test_user@localhost;
---replace_regex /10\d\d\d\d/MYSQL_VERSION_ID/
---error ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE
+#--replace_regex /10\d\d\d\d/MYSQL_VERSION_ID/
+#--error ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE
 set default role test_role for root@localhost;
 drop role test_role;
 drop user test_user@localhost;

sql/sql_base.cc

@@ -5355,8 +5355,7 @@ static bool fix_all_session_vcol_exprs(THD *thd, TABLE_LIST *tables)
   @retval TRUE          A lock wait timeout, deadlock or out of memory.
 */
 
-bool lock_tables(THD *thd, TABLE_LIST *tables, uint count,
-                 uint flags)
+bool lock_tables(THD *thd, TABLE_LIST *tables, uint count, uint flags)
 {
   TABLE_LIST *table;
   DBUG_ENTER("lock_tables");