exported codegen_preproc

--- a/src/HOL/Tools/inductive_set_package.ML	Thu Nov 06 12:30:49 2008 +0100
+++ b/src/HOL/Tools/inductive_set_package.ML	Fri Nov 07 08:57:15 2008 +0100
@@ -22,6 +22,7 @@
     (Name.binding * string option * mixfix) list ->
     (Attrib.binding * string) list -> (Facts.ref * Attrib.src list) list ->
     local_theory -> InductivePackage.inductive_result * local_theory
+  val codegen_preproc: theory -> thm list -> thm list
   val setup: theory -> theory
 end;