fix crash when connect to mysql4.1
fix crash when connect to mysql4.1

helight/helight_code,helight/helight_code,hyperworks/mysql,helight/helight_code,jockchou/mysql,Freeaqingme/golang-sql-driver-mysql,helight/helight_code,cxflag203/mysql,helight/helight_code,netroby/mysql,zhgo/mysql,siriele/mysql,tmulchay/mysql,eklitzke/mysql,hebihui/mysql,bookerzzz/mysql,cw2018/mysql,helight/helight_code,Frca/mysql,Go-SQL-Driver/MySQL,helight/helight_code,go-sql-driver/mysql,aperera/mysql,nanata1115/mysql,yonglehou/mysql,LightKool/mysql-go,bookerzzz/mysql,segmentio/mysql,Vorstack/mysql,eXcomm/gomysql,rafaeljusto/mysql,segmentio/mysql,VividCortex/mysql,helight/helight_code,dalinaum/go-mysql-driver,methane/mysql,wfxiang08/mysql,muthusubbu459/mysql,chinanjjohn2012/mysql,joshuaprunier/mysql,methane/mysql,yyljlyy/mysql,rlowe/mysql,springning/mysql,sunjian1/mysql,roth1002/mysql,LightKool/mysql-go,helight/helight_code,beego/mysql,VividCortex/mysql,henrylee2cn/mysql