BUG#54509: rpl_show_slave_running crashes the server sporadically
BUG#54509: rpl_show_slave_running crashes the server sporadically

Problem: SQL and IO thread were racing for the IO_CACHE. The former to
flush it, the latter to close it. In some cases this would cause the
SQL thread to lock an invalid IO_CACHE mutex (it had been destroyed by
IO thread). This would happen when SQL thread was initializing the
master.info

Solution: We solve this by locking the log and checking if it is
hot. If it is we keep the log while seeking. Otherwise we release it
right away, because a log can get from hot to cold, but not from cold
to hot.
flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,natsys/mariadb_10.2,slanterns/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,ollie314/server,ollie314/server,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2