Avoid DisplayList* hitting the JNI layer

Keep the actual display list type internal to HWUI/native
avoids requiring that the recording type fits in a jlong

aka, opens up a usage of value types here instead

Test: boots
Change-Id: Idf5a4acc7dbcb61e6742a6bf6369bd351f595be4
diff --git a/libs/hwui/RenderNode.h b/libs/hwui/RenderNode.h
index 6d5e62e..1eaf0d4 100644
--- a/libs/hwui/RenderNode.h
+++ b/libs/hwui/RenderNode.h
@@ -101,6 +101,7 @@
     enum ReplayFlag { kReplayFlag_ClipChildren = 0x1 };
 
     void setStagingDisplayList(DisplayList* newData);
+    void discardStagingDisplayList();
 
     void output();
     int getUsageSize();