[gtk+/portal] Implement check button support for GtkFileChooserNativePortal

[Matthias Clasen <matthiasc src gnome org>]

commit d7fc250965504966b846bfb26a0f1b36c1dbc470
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jun 27 20:56:49 2016 -0400

    Implement check button support for GtkFileChooserNativePortal

 gtk/gtkfilechoosernativeportal.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkfilechoosernativeportal.c b/gtk/gtkfilechoosernativeportal.c
index 1dbeea9..29ce73c 100644
--- a/gtk/gtkfilechoosernativeportal.c
+++ b/gtk/gtkfilechoosernativeportal.c
@@ -243,9 +243,10 @@ gtk_file_chooser_native_choice_to_variant (GtkFileChooserNativeChoice *choice)
   int i;
 
   g_variant_builder_init (&choices, G_VARIANT_TYPE ("a(ss)"));
-  for (i = 0; choice->options[i]; i++)
+  if (choice->options)
     {
-      g_variant_builder_add (&choices, "(&s&s)", choice->options[i], choice->option_labels[i]);
+      for (i = 0; choice->options[i]; i++)
+        g_variant_builder_add (&choices, "(&s&s)", choice->options[i], choice->option_labels[i]);
     }
 
   return g_variant_new ("(&s&s a(ss)&s)",