ext.auth: return nil instead of OkConnect

This allows falling through to a next `ConnectHandler` is authentication succeeds making if easier to combine with other `ConnectHandler`s.

ext/auth/basic.go

@@ -68,7 +68,7 @@ func BasicConnect(realm string, f func(user, passwd string) bool) goproxy.HttpsH
  ctx.Resp = BasicUnauthorized(ctx.Req, realm)
  return goproxy.RejectConnect, host
  }
- return goproxy.OkConnect, host
+ return nil, host
  })
 }