fixed illegal recursion (missing redirection to inserted node)

com.oracle.truffle.r.nodes.builtin/src/com/oracle/truffle/r/nodes/builtin/base/Prod.java

@@ -49,7 +49,7 @@ public abstract class Prod extends RBuiltinNode {
             prodRecursive = insert(ProdFactory.create(new RNode[1], getBuiltin(), getSuppliedArgsNames()));
         }
         // TODO: evantually handle multiple vectors properly
-        return executeObject(frame, args.getValues()[0]);
+        return prodRecursive.executeObject(frame, args.getValues()[0]);
     }
 
     @Specialization