From: Etienne Millon <me@emillon.org>
Subject: Remove deprecated header in sigccompat.h

libsigc++ 2.5.2 removed the <sigc++/object.h> header as it was useless.
Removing the #include directive makes the build succeed with later versions of
libsigc++.

--- a/src/gtk/sigccompat.h
+++ b/src/gtk/sigccompat.h
@@ -25,7 +25,6 @@
 #include <sigc++/connection.h>
 
 #include <sigc++/slot.h>
-#include <sigc++/object.h>
 #include <sigc++/functors/mem_fun.h>