MDEV-6646 : global.wsrep_causal_reads no longer honored
MDEV-6646 : global.wsrep_causal_reads no longer honored

During THD initialization, the value of wsrep_causal_reads (now
being exclusively handled via wsrep_sync_wait, lp:1277053) was
being ignored. Fixed by updating wsrep_sync_wait appropriately.


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