Plumb context through for serialization.

Change-Id: I2a49f57aa7576604deeac898a7cceb36ae68d66f
diff --git a/rsElement.h b/rsElement.h
index b86d3bc..57698f4 100644
--- a/rsElement.h
+++ b/rsElement.h
@@ -105,7 +105,7 @@
     uint32_t getBitsUnpadded() const {return mBitsUnpadded;}
 
     void dumpLOGV(const char *prefix) const;
-    virtual void serialize(OStream *stream) const;
+    virtual void serialize(Context *rsc, OStream *stream) const;
     virtual RsA3DClassID getClassId() const { return RS_A3D_CLASS_ID_ELEMENT; }
     static Element *createFromStream(Context *rsc, IStream *stream);