lib/sod.h: Make the `_vt' member of `sod_instance' be pointer-to-const.

diff --git a/lib/sod.h b/lib/sod.h
index cb6b046..8270895 100644 (file)
--- a/lib/sod.h
+++ b/lib/sod.h
@@ -53,7 +53,7 @@ struct sod_vtable {
  * these.
  */
 struct sod_instance {
-  struct sod_vtable *_vt;              /* Pointer to (chain's) vtable */
+  const struct sod_vtable *_vt;                /* Pointer to (chain's) vtable */
 };
 
 /* Information about a particular chain of superclasses.  In each class,