[libdazzle] graph-model: fix spelling

[Christian Hergert <chergert src gnome org>]

commit c089b5b2f81160bdc8f7f0835842f72cebaf65cc
Author: Christian Hergert <chergert redhat com>
Date:   Tue Aug 21 12:53:11 2018 -0700

    graph-model: fix spelling

 src/graphing/dzl-graph-model.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/graphing/dzl-graph-model.c b/src/graphing/dzl-graph-model.c
index 883d859..66e51af 100644
--- a/src/graphing/dzl-graph-model.c
+++ b/src/graphing/dzl-graph-model.c
@@ -374,7 +374,7 @@ dzl_graph_view_model_iter_set (DzlGraphModelIter *iter,
     }
 
   if (column_id != -1)
-    g_critical ("Invalid column sentinal: %d", column_id);
+    g_critical ("Invalid column sentinel: %d", column_id);
 
 cleanup:
   va_end (args);
@@ -416,7 +416,7 @@ dzl_graph_view_model_iter_get (DzlGraphModelIter *iter,
     }
 
   if (column_id != -1)
-    g_critical ("Invalid column sentinal: %d", column_id);
+    g_critical ("Invalid column sentinel: %d", column_id);
 
 cleanup:
   va_end (args);