[gtk+] widget: Constify state parameter of propagate_state

[Timm Bäder <baedert src gnome org>]

commit e70a3fab0dc5310f2268944df5b114cf73a81c24
Author: Timm Bäder <mail baedert org>
Date:   Tue Aug 1 21:31:24 2017 +0200

    widget: Constify state parameter of propagate_state
    
    Makes sense.

 gtk/gtkwidget.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index a034614..5edc2a2 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -673,8 +673,8 @@ static void             gtk_widget_pop_verify_invariants        (GtkWidget
 #endif
 static PangoContext*   gtk_widget_peek_pango_context           (GtkWidget        *widget);
 static void            gtk_widget_update_pango_context         (GtkWidget        *widget);
-static void            gtk_widget_propagate_state              (GtkWidget        *widget,
-                                                                GtkStateData     *data);
+static void             gtk_widget_propagate_state              (GtkWidget          *widget,
+                                                                 const GtkStateData *data);
 static void             gtk_widget_update_alpha                 (GtkWidget        *widget);
 
 static gint            gtk_widget_event_internal               (GtkWidget        *widget,
@@ -10845,8 +10845,8 @@ _gtk_widget_synthesize_crossing (GtkWidget       *from,
 }
 
 static void
-gtk_widget_propagate_state (GtkWidget    *widget,
-                            GtkStateData *data)
+gtk_widget_propagate_state (GtkWidget          *widget,
+                            const GtkStateData *data)
 {
   GtkWidgetPrivate *priv = widget->priv;
   GtkStateFlags new_flags, old_flags = priv->state_flags;