[libdazzle] signal-group: remove unbind from class

[Christian Hergert <chergert src gnome org>]

commit 96289a90556d165fba4f7dd0c7a251fe4868cef3
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jul 1 19:32:30 2017 -0700

    signal-group: remove unbind from class
    
    This wasn't correct nor actually used (and the class is not
    inheritable) so we can remove this without breaking ABI.

 src/bindings/dzl-signal-group.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/src/bindings/dzl-signal-group.c b/src/bindings/dzl-signal-group.c
index b559aad..1e7c65b 100644
--- a/src/bindings/dzl-signal-group.c
+++ b/src/bindings/dzl-signal-group.c
@@ -62,10 +62,8 @@ struct _DzlSignalGroupClass
 {
   GObjectClass parent_class;
 
-  void (*bind)   (DzlSignalGroup *self,
-                  GObject        *target);
-  void (*unbind) (DzlSignalGroup *self,
-                  GObject        *target);
+  void (*bind) (DzlSignalGroup *self,
+                GObject        *target);
 };
 
 typedef struct