Bug #16680313: CLIENT DOESN'T READ PLUGIN-DIR FROM MY.CNF SET BY       MYSQL_READ_DEFAULT_FILE Parsing of the plugin-dir config file option was not working due to a typo. Fixed the typo. No test case can be added due to lack of support for  defaults-exitra-file testing in mysql-test-run.pl. Thanks to Sinisa for contributing the fix.
Bug #16680313: CLIENT DOESN'T READ PLUGIN-DIR FROM MY.CNF SET BY
      MYSQL_READ_DEFAULT_FILE
Parsing of the plugin-dir config file option was not working due to a typo.
Fixed the typo. No test case can be added due to lack of support for 
defaults-exitra-file testing in mysql-test-run.pl.
Thanks to Sinisa for contributing the fix.

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