fix build with utf-8 connection string option to mysql (#1159)
fix build with utf-8 connection string option to mysql (#1159)


airbnb/caravel,apache/incubator-superset,mistercrunch/panoramix,airbnb/superset,wbsljh/caravel-aidp,apache/incubator-superset,ArijanaBrlek/superset,robert-digit/superset,francisliyy/caravel-aidp,asdf2014/superset,airbnb/superset,ArijanaBrlek/superset,apache/incubator-superset,SingTel-DataCo/incubator-superset,BRD-CD/superset,ArijanaBrlek/superset,apache/incubator-superset,mistercrunch/panoramix,ArijanaBrlek/superset,dmigo/incubator-superset,FrederichCheng/incubator-superset,robert-digit/superset,FrederichCheng/incubator-superset,alanmcruickshank/superset-dev,zhouyao1994/incubator-superset,dmigo/incubator-superset,francisliyy/caravel-aidp,timifasubaa/incubator-superset,jeromecn/caravel_viz_full,massgov/incubator-superset,wbsljh/caravel,airbnb/caravel,alanmcruickshank/superset-dev,airbnb/superset,wbsljh/caravel,francisliyy/caravel-aidp,wbsljh/caravel-aidp,timifasubaa/incubator-superset,robert-digit/superset,airbnb/superset,zhouyao1994/incubator-superset,dmigo/incubator-superset,airbnb/caravel,timifasubaa/incubator-superset,SingTel-DataCo/incubator-superset,asdf2014/superset,SingTel-DataCo/incubator-superset,wbsljh/caravel,asdf2014/superset,dmigo/incubator-superset,alanmcruickshank/superset-dev,timifasubaa/incubator-superset,wbsljh/caravel,FrederichCheng/incubator-superset,nekia/incubator-superset-dev,francisliyy/caravel-aidp,zhouyao1994/incubator-superset,jeromecn/caravel_viz_full,BRD-CD/superset,apache/incubator-superset,alanmcruickshank/superset-dev,asdf2014/superset,mistercrunch/panoramix,zhouyao1994/incubator-superset,BRD-CD/superset,BRD-CD/superset,wbsljh/caravel-aidp,zhouyao1994/incubator-superset,SingTel-DataCo/incubator-superset,jeromecn/caravel_viz_full,massgov/incubator-superset,mistercrunch/panoramix,nekia/incubator-superset-dev,FrederichCheng/incubator-superset,nekia/incubator-superset-dev,wbsljh/caravel-aidp,massgov/incubator-superset,massgov/incubator-superset,nekia/incubator-superset-dev,robert-digit/superset,jeromecn/caravel_viz_full,airbnb/caravel