[gtk] box: Remove an unnecessary include

[Timm Bäder <baedert src gnome org>]

commit 1362609120f6e2a63ac531a5df69b2c1cd1b13a9
Author: Timm Bäder <mail baedert org>
Date:   Wed Feb 7 20:08:19 2018 +0100

    box: Remove an unnecessary include

 gtk/gtkbox.c | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/gtk/gtkbox.c b/gtk/gtkbox.c
index aa249c08f7..892f5b7c4e 100644
--- a/gtk/gtkbox.c
+++ b/gtk/gtkbox.c
@@ -78,7 +78,6 @@
 
 #include "gtkbox.h"
 #include "gtkboxprivate.h"
-#include "gtkcontainerprivate.h"
 #include "gtkcssnodeprivate.h"
 #include "gtkcsspositionvalueprivate.h"
 #include "gtkintl.h"