* move a capability from a virtual handler method to table_flags()
 * rephrase error messages to avoid hard-coded English parts
 * admit in test cases that they need xtradb, not innodb

mysql-test/suite/vcol/t/rpl_vcol.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_blocked_sql_funcs_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_column_def_options_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_handler_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_ins_upd_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_keys_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_non_stored_columns_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_partition_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_select_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_supported_sql_funcs_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_trigger_sp_innodb.test:
  this test needs xtradb, it will fail with innodb
mysql-test/suite/vcol/t/vcol_view_innodb.test:
  this test needs xtradb, it will fail with innodb
sql/ha_partition.h:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
sql/handler.h:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
sql/share/errmsg.txt:
  no hard-coded english parts in the error messages (ER_UNSUPPORTED_ACTION_ON_VIRTUAL_COLUMN)
sql/sql_table.cc:
  no hard-coded english parts in the error messages
sql/table.cc:
  * check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
  * no "csv workaround" is needed
  * no hard-coded english parts in the error messages
storage/maria/ha_maria.cc:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
storage/maria/ha_maria.h:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
storage/myisam/ha_myisam.cc:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
storage/myisam/ha_myisam.h:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
storage/xtradb/handler/ha_innodb.cc:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS
storage/xtradb/handler/ha_innodb.h:
  check_if_supported_virtual_columns() -> HA_CAN_VIRTUAL_COLUMNS