Isolate tiling clip state from snapshot

bug:8409891

Snapshots frequently have their clip overwritten due to applying
deferred state - now, store tiling clip information in a separate
rect, outside of the snapshot so it isn't overwritten.

Change-Id: I21ca4c45dcd802eae99e8de86f11525196777ccb
diff --git a/libs/hwui/Snapshot.h b/libs/hwui/Snapshot.h
index ffd4729..cc6d0cd 100644
--- a/libs/hwui/Snapshot.h
+++ b/libs/hwui/Snapshot.h
@@ -228,6 +228,8 @@
      */
     float alpha;
 
+    void dump() const;
+
 private:
     void ensureClipRegion();
     void copyClipRectFromRegion();