mysql: add references priv in AllColumnPrivs (pingcap#1358)

Author: unconsolable

mysql/privs.go

@@ -309,7 +309,7 @@ var AllDBPrivs = Privileges{SelectPriv, InsertPriv, UpdatePriv, DeletePriv, Crea
 var AllTablePrivs = Privileges{SelectPriv, InsertPriv, UpdatePriv, DeletePriv, CreatePriv, DropPriv, IndexPriv, ReferencesPriv, AlterPriv, CreateViewPriv, ShowViewPriv}
 
 // AllColumnPrivs is all the privileges in column scope.
-var AllColumnPrivs = Privileges{SelectPriv, InsertPriv, UpdatePriv}
+var AllColumnPrivs = Privileges{SelectPriv, InsertPriv, UpdatePriv, ReferencesPriv}
 
 // StaticGlobalOnlyPrivs is all the privileges only in global scope and different from dynamic privileges.
 var StaticGlobalOnlyPrivs = Privileges{ProcessPriv, ShowDBPriv, SuperPriv, CreateUserPriv, CreateTablespacePriv, ShutdownPriv, ReloadPriv, FilePriv, ReplicationClientPriv, ReplicationSlavePriv, ConfigPriv}