table: fix PriorityFifoPolicy memory leak

Change-Id: I1bd7d75b3a24b854a0a07e1fa197ef793f66192f
Refs: #3236
diff --git a/daemon/table/cs-policy-priority-fifo.hpp b/daemon/table/cs-policy-priority-fifo.hpp
index 93ae884..0078c71 100644
--- a/daemon/table/cs-policy-priority-fifo.hpp
+++ b/daemon/table/cs-policy-priority-fifo.hpp
@@ -75,6 +75,9 @@
 public:
   PriorityFifoPolicy();
 
+  virtual
+  ~PriorityFifoPolicy();
+
 public:
   static const std::string POLICY_NAME;