mk_const_id now checks for clashes with reserved ML identifiers.

--- a/src/Pure/codegen.ML	Wed Mar 27 20:45:03 2002 +0100
+++ b/src/Pure/codegen.ML	Thu Mar 28 16:28:12 2002 +0100
@@ -248,7 +248,9 @@
     (if not (Symbol.is_letter x) then "id" else "") ^ check_str xs
   end;
 
-val mk_const_id = gen_mk_id Sign.constK I;
+val mk_const_id = gen_mk_id Sign.constK
+  (fn s => if s mem ThmDatabase.ml_reserved then s ^ "_const" else s);
+
 val mk_type_id = gen_mk_id Sign.typeK
   (fn s => if s mem ThmDatabase.ml_reserved then s ^ "_type" else s);