MDEV-4505 Buffer overrun when processing --log-bin parameter without file name
MDEV-4505 Buffer overrun when processing --log-bin parameter without file name

because --log-bin sets opt_bin_logname to ""
(same for any OPT_ARG GET_STR (or GET_STR_ALLOC) option)

davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server,flynn1973/mariadb-aix,flynn1973/mariadb-aix,slanterns/server,ollie314/server,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi