[gtk+] GtkApplication: Prevent more crashes around shutdown

[Matthias Clasen <matthiasc src gnome org>]

commit 7603b527909118f54502e512efcb829e3394a522
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Apr 10 08:03:24 2015 -0400

    GtkApplication: Prevent more crashes around shutdown
    
    gtk_application_shutdown clears the impl member, so all
    callbacks, signal handlers, etc that might still be triggered
    between a shutdown call and the return from the mainloop
    better be prepared to deal with impl being NULL.

 gtk/gtkapplication.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkapplication.c b/gtk/gtkapplication.c
index 91ef355..cdc792d 100644
--- a/gtk/gtkapplication.c
+++ b/gtk/gtkapplication.c
@@ -1780,14 +1780,16 @@ void
 gtk_application_handle_window_realize (GtkApplication *application,
                                        GtkWindow      *window)
 {
-  gtk_application_impl_handle_window_realize (application->priv->impl, window);
+  if (application->priv->impl)
+    gtk_application_impl_handle_window_realize (application->priv->impl, window);
 }
 
 void
 gtk_application_handle_window_map (GtkApplication *application,
                                    GtkWindow      *window)
 {
-  gtk_application_impl_handle_window_map (application->priv->impl, window);
+  if (application->priv->impl)
+    gtk_application_impl_handle_window_map (application->priv->impl, window);
 }
 
 /**