[gtk+] treeviewcolumn: use g_clear_object when freeing cursor

[Christian Hergert <chergert src gnome org>]

commit 3c775eb2b808c6f7b1b7a6eab5fefe1085d74c5a
Author: Christian Hergert <chergert redhat com>
Date:   Tue Sep 27 12:41:55 2016 -0700

    treeviewcolumn: use g_clear_object when freeing cursor
    
    There is the chance that the cursor returned NULL on systems
    with missing cursors. This defensively handles that by checking
    for a NULL cursor.

 gtk/gtktreeviewcolumn.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtktreeviewcolumn.c b/gtk/gtktreeviewcolumn.c
index 055d938..48b6fcd 100644
--- a/gtk/gtktreeviewcolumn.c
+++ b/gtk/gtktreeviewcolumn.c
@@ -1349,7 +1349,7 @@ _gtk_tree_view_column_realize_button (GtkTreeViewColumn *column)
 
   gtk_tree_view_column_update_button (column);
 
-  g_object_unref (attr.cursor);
+  g_clear_object (&attr.cursor);
 }
 
 void