Fix Bug# 58459 - assert slot->in_use == FALSE while starting purge thread.
Fix Bug# 58459 - assert slot->in_use == FALSE while starting purge thread.

Fix a race condition in srv_master_thread(). We need to acquire the kernel
mutex before calling srv_table_reserve_slot(). Add a mutex_own() assertion
in srv_table_reserve_slot().

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