face: allow enabling/disabling congestion marking through config file

refs #4465

Change-Id: I888b83b1fdbe8e3fc36a902bf7af52147807d829
diff --git a/daemon/face/udp-factory.hpp b/daemon/face/udp-factory.hpp
index 1153a7a..62f59ee 100644
--- a/daemon/face/udp-factory.hpp
+++ b/daemon/face/udp-factory.hpp
@@ -133,6 +133,7 @@
 
 private:
   std::map<udp::Endpoint, shared_ptr<UdpChannel>> m_channels;
+  bool m_wantCongestionMarking;
 
   struct MulticastConfig
   {