need go1.9 (#5310)
need go1.9 (#5310)

fix syntax error: unexpected = in type declaration. need go1.9
Cofyc/tidb,ngaut/tidb,qiuyesuifeng/tidb,EvilMcJerkface/tidb,coocood/tidb,ngaut/tidb,Cofyc/tidb,pingcap/tidb,cosmtrek/tidb,cosmtrek/tidb,tiancaiamao/tidb,ngaut/tidb,kyle-wang/tidb,yangwenmai/tidb,pingcap/tidb,yangwenmai/tidb,qiuyesuifeng/tidb,c4pt0r/tidb,mccxj/tidb,EvilMcJerkface/tidb,c4pt0r/tidb,c4pt0r/tidb,kyle-wang/tidb,pingcap/tidb,pingcap/tidb,ngaut/tidb,Nify/tidb,spongedu/tidb,ngaut/tidb,pingcap/tidb,ming-relax/tidb,kyle-wang/tidb,wusphinx/tidb,c4pt0r/tidb,spongedu/tidb,pingcap/tidb,mccxj/tidb,c4pt0r/tidb,CodeRushing/tidb,kyle-wang/tidb,CodeRushing/tidb,XuHuaiyu/tidb,c4pt0r/tidb,kyle-wang/tidb,ngaut/tidb,Nify/tidb,coocood/tidb,ming-relax/tidb,wusphinx/tidb,XuHuaiyu/tidb,kyle-wang/tidb,tiancaiamao/tidb