[gtkmm] CellRendererProgress:_property_renderable(): Avoid infinite loop.

[Murray Cumming <murrayc src gnome org>]

commit 93892716146caec4f3d6aaa828ea15ce5d17a4ef
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Mar 8 13:35:33 2016 +0100

    CellRendererProgress:_property_renderable(): Avoid infinite loop.
    
    Found by clang++.

 gtk/src/cellrendererprogress.ccg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/cellrendererprogress.ccg b/gtk/src/cellrendererprogress.ccg
index 800700c..1b3bb47 100644
--- a/gtk/src/cellrendererprogress.ccg
+++ b/gtk/src/cellrendererprogress.ccg
@@ -23,7 +23,7 @@ namespace Gtk
 
 Glib::PropertyProxy_Base CellRendererProgress::_property_renderable()
 {
-  return _property_renderable();
+  return property_value();
 }