[gtk/wip/ebassi/constraint-layout] docs: Add more private headers to the list

[Emmanuele Bassi <ebassi src gnome org>]

commit 04aaf02881acee3e603835ac1062f6525de096c8
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Jul 2 09:48:17 2019 +0100

    docs: Add more private headers to the list
    
    The various GtkConstraint private API should not be scanned for
    documentation.

 docs/reference/gtk/meson.build | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/docs/reference/gtk/meson.build b/docs/reference/gtk/meson.build
index 53d88ee9aa..5d0f0c8142 100644
--- a/docs/reference/gtk/meson.build
+++ b/docs/reference/gtk/meson.build
@@ -23,6 +23,13 @@ private_headers = [
   'gtkcolorswatchprivate.h',
   'gtkcomboboxprivate.h',
   'gtkcontainerprivate.h',
+  'gtkconstraintexpressionprivate.h',
+  'gtkconstraintguideprivate.h',
+  'gtkconstraintlayoutprivate.h',
+  'gtkconstraintprivate.h',
+  'gtkconstraintsolverprivate.h',
+  'gtkconstrainttypesprivate.h',
+  'gtkconstraintvflparserprivate.h',
   'gtkcssanimatedstyleprivate.h',
   'gtkcssanimationprivate.h',
   'gtkcssarrayvalueprivate.h',