[libxml++] Still more use of nullptr instead of 0

[Kjell Ahlstedt <kjellahl src gnome org>]

commit c2f8011cf64d5599ca64fc40cb7219d50f0dd9de
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Fri Oct 9 16:28:36 2015 +0200

    Still more use of nullptr instead of 0

 libxml++/io/parserinputbuffer.cc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libxml++/io/parserinputbuffer.cc b/libxml++/io/parserinputbuffer.cc
index b1732b4..e4d2473 100644
--- a/libxml++/io/parserinputbuffer.cc
+++ b/libxml++/io/parserinputbuffer.cc
@@ -54,7 +54,7 @@ namespace xmlpp
     bool result = do_close();
     // the underlying structure is being freed by libxml, the pointer will soon be
     // invalid.
-    impl_ = 0;
+    impl_ = nullptr;
 
     return result;
   }