in ha_delete_table()
* only convert ENOENT and HA_ERR_NO_SUCH_TABLE to warnings
* only return real error codes (that is, not ENOENT and
not HA_ERR_NO_SUCH_TABLE)
* intercept HA_ERR_ROW_IS_REFERENCED to generate backward
compatible ER_ROW_IS_REFERENCED
in mysql_rm_table_no_locks()
* no special code to handle HA_ERR_ROW_IS_REFERENCED
* no special code to handle ENOENT and HA_ERR_NO_SUCH_TABLE
* return multi-table error ER_BAD_TABLE_ERROR <table list> only
when there were many errors, not when there were many
tables to drop (but only one table generated an error)
storage/innobase/handler/handler0alter.cc:
for NEWDATE key_type says unsigned, thus col->prtype says unsigned,
but field->flags says signed. Use the same flag for value retrieval
that was used for value storage.
