[gtk+] Avoid more compiler warnings

[Matthias Clasen <matthiasc src gnome org>]

commit 147e0512c54645eee5ea13370b67da4c2dc1682f
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Mar 23 16:15:26 2017 +0000

    Avoid more compiler warnings

 gtk/gtkrecentmanager.c |    2 +-
 gtk/gtkscalebutton.c   |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkrecentmanager.c b/gtk/gtkrecentmanager.c
index 4a9552d..8182ff5 100644
--- a/gtk/gtkrecentmanager.c
+++ b/gtk/gtkrecentmanager.c
@@ -987,7 +987,7 @@ gtk_recent_manager_add_full (GtkRecentManager    *manager,
 
   g_bookmark_file_set_mime_type (priv->recent_items, uri, data->mime_type);
 
-  if (data->groups && data->groups[0] != '\0')
+  if (data->groups && ((char*)data->groups)[0] != '\0')
     {
       gint j;
 
diff --git a/gtk/gtkscalebutton.c b/gtk/gtkscalebutton.c
index 27d668a..8423cd6 100644
--- a/gtk/gtkscalebutton.c
+++ b/gtk/gtkscalebutton.c
@@ -985,7 +985,7 @@ gtk_scale_button_update_icon (GtkScaleButton *button)
   const gchar *name;
   guint num_icons;
 
-  if (!priv->icon_list || priv->icon_list[0] == '\0')
+  if (!priv->icon_list || ((char*)priv->icon_list)[0] == '\0')
     {
       gtk_image_set_from_icon_name (GTK_IMAGE (priv->image),
                                     "image-missing",