[gtk/wip/chergert/glproto] update copyright

[Christian Hergert <chergert src gnome org>]

commit e4c9ba6b09bdef7997b6d5e0abb9e1e1812cfd31
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 4 14:52:00 2021 -0800

    update copyright

 gsk/next/gskgldriver.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gsk/next/gskgldriver.c b/gsk/next/gskgldriver.c
index ae77a16ef8..aff92d06c9 100644
--- a/gsk/next/gskgldriver.c
+++ b/gsk/next/gskgldriver.c
@@ -1,5 +1,8 @@
 /* gskgldriver.c
  *
+ * Copyright 2017 Timm Bäder <mail baedert org>
+ * Copyright 2018 Matthias Clasen <mclasen redhat com>
+ * Copyright 2018 Alexander Larsson <alexl redhat com>
  * Copyright 2020 Christian Hergert <chergert redhat com>
  *
  * This library is free software; you can redistribute it and/or