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
diff --git a/libs/hwui/TreeInfo.h b/libs/hwui/TreeInfo.h
index b37f2cf..f2766d6 100644
--- a/libs/hwui/TreeInfo.h
+++ b/libs/hwui/TreeInfo.h
@@ -39,7 +39,7 @@
     virtual void onError(const std::string& message) = 0;
 
 protected:
-    ~ErrorHandler() {}
+    virtual ~ErrorHandler() {}
 };
 
 class TreeObserver {