Maintain compatibility with the structures in rsAllocation.h

Change-Id: I99110a0cbb28faa8c13b1b7ec05920f51cf13620
diff --git a/lib/ScriptCRT/rs_core.c b/lib/ScriptCRT/rs_core.c
index efecf8e..e89e368 100644
--- a/lib/ScriptCRT/rs_core.c
+++ b/lib/ScriptCRT/rs_core.c
@@ -40,6 +40,7 @@
             bool hasReferences;
             void * usrPtr;
             int32_t surfaceTextureID;
+            void * wndSurface;
         } state;
 
         struct DrvState {