[gtkmm] button: Drop clicked(), as it's gone in GTK master

[Daniel Boles <dboles src gnome org>]

commit 283218dadf5d74ef2b67c1cbecacca2931337a7a
Author: Daniel Boles <dboles src gnome org>
Date:   Sun May 19 18:25:21 2019 +0100

    button: Drop clicked(), as it's gone in GTK master
    
    See GTK commit bcfff5e46934cb7bb9bae0730d557a3ed0faf163:
    
    >>>
    This is not an api we want to propagate anymore.
    If you need to, you can still emit the "clicked"
    action signal on a button using g_signal_emit_by_name.
    >>>

 gtk/src/button.hg | 2 --
 1 file changed, 2 deletions(-)
---
diff --git a/gtk/src/button.hg b/gtk/src/button.hg
index 79ebfd02..8a9a9999 100644
--- a/gtk/src/button.hg
+++ b/gtk/src/button.hg
@@ -65,8 +65,6 @@ public:
   //But set_icon_name() and set_image_from_icon_name() are replacements.
   _IGNORE(gtk_button_new_from_icon_name)
 
-  _WRAP_METHOD(void clicked(), gtk_button_clicked)
-
   _WRAP_METHOD(void set_relief(ReliefStyle relief), gtk_button_set_relief)
   _WRAP_METHOD(ReliefStyle get_relief() const, gtk_button_get_relief)