[gtk] gtk-demo: Don't include "gtk.h"

[Benjamin Otte <otte src gnome org>]

commit 101298c54d3aef6aca4a3a6248eece0345c8aabc
Author: Benjamin Otte <otte redhat com>
Date:   Wed Dec 11 20:00:46 2019 +0100

    gtk-demo: Don't include "gtk.h"

 demos/gtk-demo/fontplane.c | 2 --
 1 file changed, 2 deletions(-)
---
diff --git a/demos/gtk-demo/fontplane.c b/demos/gtk-demo/fontplane.c
index 26f301d4fc..b7b07cb7ad 100644
--- a/demos/gtk-demo/fontplane.c
+++ b/demos/gtk-demo/fontplane.c
@@ -19,8 +19,6 @@
 
 #include "fontplane.h"
 
-#include "gtk.h"
-
 enum {
   PROP_0,
   PROP_WEIGHT_ADJUSTMENT,