[Maria-docs] table_definition_cache on mariadb.com

https://mariadb.com/kb/en/mariadb/documentation/optimization-and-tuning/syst... Default Value: 400 Range: 400 to 64524288 In the code: VALID_RANGE(TABLE_DEF_CACHE_MIN, 512*1024), For MySQL: http://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html#sysvar_t... Default 400 Min Value 400 Max Value 524288