[sysprof] callgraph-view: compare nodes by using data field

[Christian Hergert <chergert src gnome org>]

commit 40eb9a2c4ec3ecee6bfef3ff5a680cc135497cdf
Author: Christian Hergert <chergert redhat com>
Date:   Tue Nov 15 22:03:36 2016 -0800

    callgraph-view: compare nodes by using data field
    
    We could have multiple StackNodes that point at the same data. However
    we might not have pointer equality. This uses the data pointer that nodes
    point at to determine equality.

 lib/sp-callgraph-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/sp-callgraph-view.c b/lib/sp-callgraph-view.c
index a960e14..8ea1683 100644
--- a/lib/sp-callgraph-view.c
+++ b/lib/sp-callgraph-view.c
@@ -526,7 +526,7 @@ sp_callgraph_view_set_node (SpCallgraphView *self,
                               COLUMN_POINTER, &item,
                               -1);
 
-          if (item == node)
+          if (item != NULL && item->data == node->data)
             {
               GtkTreeSelection *selection;