routing: use unique_ptr for signal container

Change-Id: I1912f8630d0e26d8c25c2050208f6b8b0ffd9009
refs: #4268
diff --git a/src/route/routing-table.hpp b/src/route/routing-table.hpp
index 274853e..60da254 100644
--- a/src/route/routing-table.hpp
+++ b/src/route/routing-table.hpp
@@ -115,7 +115,7 @@
   writeLog(int hyperbolicState);
 
 public:
-  std::shared_ptr<AfterRoutingChange> afterRoutingChange;
+  std::unique_ptr<AfterRoutingChange> afterRoutingChange;
 
 PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   std::list<RoutingTableEntry> m_rTable;