fw: accept const shared_ptr<pit::Entry>& in Forwarder pipelines and Strategy actions

refs #3205

Change-Id: Ia683fb1a9e301270f99bcdd4d97493abf3dbec9f
diff --git a/daemon/fw/strategy.cpp b/daemon/fw/strategy.cpp
index 53b8935..7e668b6 100644
--- a/daemon/fw/strategy.cpp
+++ b/daemon/fw/strategy.cpp
@@ -66,7 +66,7 @@
 }
 
 void
-Strategy::sendNacks(shared_ptr<pit::Entry> pitEntry, const lp::NackHeader& header,
+Strategy::sendNacks(const shared_ptr<pit::Entry>& pitEntry, const lp::NackHeader& header,
                     std::initializer_list<const Face*> exceptFaces)
 {
   // populate downstreams with all downstreams faces