[glibmm] RefPtr: Use nullptr instead of 0.

[Murray Cumming <murrayc src gnome org>]

commit c0eb29b0b7c171a25a8a8c41cd343335b13e2303
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Nov 19 14:25:16 2015 +0100

    RefPtr: Use nullptr instead of 0.

 glib/glibmm/refptr.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/glib/glibmm/refptr.h b/glib/glibmm/refptr.h
index a7ca0fc..df12ed6 100644
--- a/glib/glibmm/refptr.h
+++ b/glib/glibmm/refptr.h
@@ -263,7 +263,7 @@ T_CppObject* RefPtr<T_CppObject>::operator->() const noexcept
 template <class T_CppObject> inline
 RefPtr<T_CppObject>::RefPtr() noexcept
 :
-  pCppObject_ (0)
+  pCppObject_ (nullptr)
 {}
 
 template <class T_CppObject> inline