Markup fix.

Doc/lib/libgc.tex

@@ -102,8 +102,8 @@ objects, call \function{collect()} before calling
 \begin{funcdesc}{get_referents}{*objs}
 Return a list of objects directly referred to by any of the arguments.
 The referents returned are those objects visited by the arguments'
-C-level \cfunction{tp_traverse} methods (if any), and may not be all
-objects actually directly reachable.  \cfunction{tp_traverse} methods
+C-level \member{tp_traverse} methods (if any), and may not be all
+objects actually directly reachable.  \member{tp_traverse} methods
 are supported only by objects that support garbage collection, and are
 only required to visit objects that may be involved in a cycle.  So,
 for example, if an integer is directly reachable from an argument, that