adjusting to longer names in PNF_Narrowing_Engine, which was overlooked in 4106258260b3

--- a/src/HOL/Tools/Quickcheck/PNF_Narrowing_Engine.hs	Thu Mar 22 21:43:26 2012 +0100
+++ b/src/HOL/Tools/Quickcheck/PNF_Narrowing_Engine.hs	Fri Mar 23 12:03:59 2012 +0100
@@ -301,7 +301,7 @@
 checkOf (Generated_Code.Universal _ f _) = (\(t : ts) -> checkOf (f t) ts)
 checkOf (Generated_Code.Existential _ f _) = (\(t : ts) -> checkOf (f t) ts)
 
-dummy = Generated_Code.Var [] (Generated_Code.SumOfProd [[]])
+dummy = Generated_Code.Narrowing_variable [] (Generated_Code.Narrowing_sum_of_products [[]])
 
 treeOf :: Int -> Generated_Code.Property -> QuantTree
 treeOf n (Generated_Code.Property _) = Node uneval