fixed EXT-4478 “Memory leak in LLChicletPanel”,

added destroying chiclet on chiclet panel item remove event;
made LLIMChiclet destructor virtual;

--HG--
branch : product-engine

indra/newview/llchiclet.cpp

@@ -1297,6 +1297,7 @@ void LLChicletPanel::removeChiclet(chiclet_list_t::iterator it)
 	mChicletList.erase(it);
 	
 	arrange();
+	(*it)->die();
 }
 
 void LLChicletPanel::removeChiclet(S32 index)

indra/newview/llchiclet.h

@@ -325,7 +325,7 @@ public:
 	};
 
 	
-	/*virtual*/ ~LLIMChiclet() {};
+	virtual ~LLIMChiclet() {};
 
 	/**
 	 * Sets IM session name. This name will be displayed in chiclet tooltip.