Replace mysql_version check with frm_version for virtual columns inside InnoDB

• Start 10.1 server, all defaults are sufficient;
• create a table as

  CREATE TABLE t1 (f1 INT, f2 INT AS (f1) VIRTUAL) ENGINE=InnoDB;

• shut down the server normally;
• start 10.3 or 10.4 server on the same datadir;
• (optionally, it doesn't affect the outcome) run mysql_upgrade;
• run

  CHECK TABLE t1;

  ALTER TABLE t1 DROP CONSTRAINT IF EXISTS x;

  The result is

  Table Op Msg_type Msg_text

  test.t1 check status OK

  ERROR 1932 (42S02) at line 2: Table 'test.t1' doesn't exist in engine

  The error log gets the warning:

  2019-05-27 1:49:53 9 [Warning] InnoDB: Table test/t1 contains 1 user defined columns in InnoDB, but 2 columns in MariaDB. Please check INFORMATION_SCHEMA.INNODB_SYS_COLUMNS and https://mariadb.com/kb/en/innodb-data-dictionary-troubleshooting/ for how to resolve the issue.

  Further attempts to use the table cause errors in the log:

  2019-05-27 1:50:18 10 [ERROR] InnoDB: Table `test`.`t1` is corrupted. Please drop the table and recreate.

A datadir pre-created as described on 10.1 aaf53ea0 is attached.

Not reproducible with 10.2, either being the new server or old server in the scenario.