Fix a compiler warning in my_gethwaddr.c:67:
Fix a compiler warning in my_gethwaddr.c:67:

mysys/my_gethwaddr.c: In function 'my_gethwaddr':
mysys/my_gethwaddr.c:67:11: error: pointer targets in assignment differ in signedness

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