Fix some wrong-thread issues around animator management

 Bug: 17372309

 Fixes a case where UI thread and RT thread both used the same method
 which wasn't safe for either of them.

 Adds additional assertions & logging in unusual circumstances to
 try and track down where the issue is occuring from.

Change-Id: I93d31a6fd0c5927259b67bdf96a475944226eee6
diff --git a/libs/hwui/AnimationContext.h b/libs/hwui/AnimationContext.h
index 900d953..9b3d5f4 100644
--- a/libs/hwui/AnimationContext.h
+++ b/libs/hwui/AnimationContext.h
@@ -98,6 +98,8 @@
 
     ANDROID_API virtual void callOnFinished(BaseRenderNodeAnimator* animator, AnimationListener* listener);
 
+    ANDROID_API virtual void destroy();
+
 private:
     friend class AnimationHandle;
     void addAnimationHandle(AnimationHandle* handle);