[gtk+] meson: gtk: add missing source file

[Emmanuele Bassi <ebassi src gnome org>]

commit aa52cbeb11efeae6eb2499f5f0cb4dc2aa12ea7e
Author: Tim-Philipp Müller <tim centricular com>
Date:   Sun Feb 12 00:42:37 2017 +0000

    meson: gtk: add missing source file

 gtk/meson.build |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/meson.build b/gtk/meson.build
index 9864ca6..5931178 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -142,6 +142,7 @@ gtk_sources = files([
   'gtkcssvalue.c',
   'gtkcsswidgetnode.c',
   'gtkcsswin32sizevalue.c',
+  'gtkdebugupdates.c',
   'gtkdialog.c',
   'gtkdragdest.c',
   'gtkdragsource.c',