[gtk+/gtk-3-22] Fix previous commit

[Emmanuele Bassi <ebassi src gnome org>]

commit 7fe07ea9062e1c3ef1f540239527c869c3d2b69b
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Oct 13 10:55:00 2017 +0100

    Fix previous commit
    
    The _gtk_widget_get_parent() private accessor is defined inside
    gtkwidgetprivate.h.

 gtk/gtkfixed.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkfixed.c b/gtk/gtkfixed.c
index 70d31f6..0e4b2bc 100644
--- a/gtk/gtkfixed.c
+++ b/gtk/gtkfixed.c
@@ -75,6 +75,7 @@
 
 #include "gtkfixed.h"
 
+#include "gtkwidgetprivate.h"
 #include "gtkprivate.h"
 #include "gtkintl.h"