[gtk/gbsneto/install-header] build: Install gtkboxlayout.h

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 3d524cc67d400074e19990bfc528ee15ce83ce35
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Mar 27 22:55:07 2019 -0300

    build: Install gtkboxlayout.h
    
    This is included by gtk.h, and thus required to build.

 gtk/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtk/meson.build b/gtk/meson.build
index 44114fb23b..dbdbbb213a 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -426,6 +426,7 @@ gtk_public_headers = files([
   'gtkbindings.h',
   'gtkborder.h',
   'gtkbox.h',
+  'gtkboxlayout.h',
   'gtkbuildable.h',
   'gtkbuilder.h',
   'gtkbutton.h',