fixed silly bug in function serializer for ML

--- a/src/Pure/Tools/codegen_serializer.ML	Fri May 12 04:20:02 2006 +0200
+++ b/src/Pure/Tools/codegen_serializer.ML	Fri May 12 10:38:00 2006 +0200
@@ -586,7 +586,9 @@
                   true
               | has_tyvars (ty1 `-> ty2) =
                   has_tyvars ty1 orelse has_tyvars ty2;
-          in if (not o has_tyvars) ty orelse fold no_eta eqs true
+          in if (null o fst o CodegenThingol.unfold_fun) ty
+              orelse (not o has_tyvars) ty
+              orelse fold no_eta eqs true
             then funn
             else (map (fn ([], rhs) => ([IVar "x"], rhs `$ IVar "x")) eqs, sctxt_ty)
           end;