MT#63171 Statistics: add dtor

This module initialises and starts the StatsUDPServer. Stop its worker
when the module is destroyed.

Change-Id: I265d7ee103866a5946b066e4e7d42376e3510cac
(cherry picked from commit 4bd36ffc89)
(cherry picked from commit 01efa15b84)

core/plug-in/stats/Statistics.cpp

@@ -36,6 +36,15 @@ StatsFactory::StatsFactory(const std::string& _app_name)
 {
 }
 
+StatsFactory::~StatsFactory()
+{
+  StatsUDPServer* stat_srv = StatsUDPServer::instance();
+  if (stat_srv) {
+    stat_srv->stop();
+    stat_srv->join();
+  }
+}
+
 int StatsFactory::onLoad()
 {
   StatsUDPServer* stat_srv = StatsUDPServer::instance();

core/plug-in/stats/Statistics.h

@@ -35,7 +35,8 @@ class StatsFactory: public AmPluginFactory
 {
 public:
   StatsFactory(const std::string& _app_name);
-    
+  ~StatsFactory();
+
   // AmPluginFactory interface
   int onLoad();
 };