Update header for forward compatibility

Change-Id: Idf38142dc073dce14741e8da005e7d2eaf9242de
diff --git a/include/private/hwui/DrawGlInfo.h b/include/private/hwui/DrawGlInfo.h
index 8028bf3..e33823e 100644
--- a/include/private/hwui/DrawGlInfo.h
+++ b/include/private/hwui/DrawGlInfo.h
@@ -31,6 +31,10 @@
     int clipRight;
     int clipBottom;
 
+    // Input: current width/height of destination surface
+    int width;
+    int height;
+
     // Input: is the render target an FBO
     bool isLayer;