TreeInfo: Make ~ErrorHandler() virtual

ErrorHandler has a pure virtual function, so we also make its
destructor virtual, to assure any children classes will get
properly destructed.

Test: TreeHugger
Change-Id: Ie072511b450d507f8764b0888d232ffac8f6d6f5

libs/hwui/TreeInfo.h

@@ -39,7 +39,7 @@ public:
     virtual void onError(const std::string& message) = 0;
 
 protected:
-    ~ErrorHandler() {}
+    virtual ~ErrorHandler() {}
 };
 
 class TreeObserver {