Add option to reflect all block members, inactive or active.

* The stages mask is more fine-grained, and each variable or block's mask
  indicates which stages it's active in.

Test/reflection.vert

@@ -172,6 +172,7 @@ struct TriangleInfo {
 
 buffer VertexCollection {
     TriangleInfo t[5];
+    uint padding[10];
 };
 
 out float outval;