made aconvc pervasive;

--- a/src/Pure/more_thm.ML	Thu May 31 18:31:36 2007 +0200
+++ b/src/Pure/more_thm.ML	Thu May 31 19:11:19 2007 +0200
@@ -192,4 +192,6 @@
 
 end;
 
+val op aconvc = Thm.aconvc;
+
 structure Thmtab = TableFun(type key = thm val ord = Thm.thm_ord);