fixed error bug

--- a/src/Pure/Tools/codegen_serializer.ML	Wed Jun 21 11:23:06 2006 +0200
+++ b/src/Pure/Tools/codegen_serializer.ML	Wed Jun 21 11:23:49 2006 +0200
@@ -267,7 +267,7 @@
       else (warning ("in function " ^ quote name ^ ", throwing away one "
         ^ "non-executable function clause"); NONE)
   in case map_filter check_eq eqs
-   of [] => error ("in function " ^ quote name ^ ", no"
+   of [] => error ("in function " ^ quote name ^ ", no "
         ^ "executable function clauses found")
     | eqs => (name, (eqs, ty))
   end;