[gtk+] Revert "treeviewcolumn: Don't leak button"

[Daniel Boles <dboles src gnome org>]

commit 161b063909783b6ad9bc5a3266b3b3b573182386
Author: Daniel Boles <dboles src gmail com>
Date:   Fri Oct 6 20:40:59 2017 +0100

    Revert "treeviewcolumn: Don't leak button"
    
    This reverts commit 2c28c627c1527d4ee2dfc4d3805f7afc482049e2.
    
    See following commits: the real problem is setting priv->button to NULL
    soon after this, so this just makes that wrong decision look more right.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788614

 gtk/gtktreeviewcolumn.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtktreeviewcolumn.c b/gtk/gtktreeviewcolumn.c
index 8e30dfe..7076153 100644
--- a/gtk/gtktreeviewcolumn.c
+++ b/gtk/gtktreeviewcolumn.c
@@ -1334,7 +1334,6 @@ _gtk_tree_view_column_unset_tree_view (GtkTreeViewColumn *column)
   if (priv->tree_view)
     {
       gtk_container_remove (GTK_CONTAINER (priv->tree_view), priv->button);
-      g_clear_object (&priv->button);
     }
   if (priv->property_changed_signal)
     {