[glibmm] Correct a comment.

[Murray Cumming <murrayc src gnome org>]

commit 4866bc0ee99bfed1e48ccd50484fbdab67782993
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Jul 27 08:22:53 2015 +0200

    Correct a comment.

 tests/glibmm_refptr_sigc_bind/main.cc |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/tests/glibmm_refptr_sigc_bind/main.cc b/tests/glibmm_refptr_sigc_bind/main.cc
index 27b54e9..38fe93b 100644
--- a/tests/glibmm_refptr_sigc_bind/main.cc
+++ b/tests/glibmm_refptr_sigc_bind/main.cc
@@ -1,7 +1,6 @@
 // Bug 564005 - Valgrind errors and crash on exit with Gtk::UIManager
 // Bug 154498 - Unnecessary warning on console: signalproxy_connectionnode.cc
 
-// libsigc++-only test case. (Or almost so. glib_refptr.h is stolen from glibmm.)
 
 #include <glibmm/refptr.h>
 #include <sigc++/sigc++.h>