Fix fountain and put the demos back in the optional build.
diff --git a/libs/rs/rsVertexArray.cpp b/libs/rs/rsVertexArray.cpp
index d0c0414..6c2002d 100644
--- a/libs/rs/rsVertexArray.cpp
+++ b/libs/rs/rsVertexArray.cpp
@@ -191,6 +191,9 @@
         if (sc->isUserVertexProgram()) {
             slot = sc->vtxAttribSlot(ct);
         } else {
+            if (mAttribs[ct].kind == RS_KIND_USER) {
+                continue;
+            }
             slot = sc->vtxAttribSlot(mAttribs[ct].kind);
         }