[retro-gtk] environment: Drop un unused private function

[Adrien Plazas <aplazas src gnome org>]

commit a385319900a26c8d2d68e25610a8450aa525c4b4
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sat Jul 31 09:20:10 2021 +0200

    environment: Drop un unused private function

 retro-runner/retro-environment.c | 7 -------
 1 file changed, 7 deletions(-)
---
diff --git a/retro-runner/retro-environment.c b/retro-runner/retro-environment.c
index 31e25f7..29e18f9 100644
--- a/retro-runner/retro-environment.c
+++ b/retro-runner/retro-environment.c
@@ -899,13 +899,6 @@ video_refresh_cb (guint8 *data,
     g_signal_emit_by_name (self, "video-output");
 }
 
-// TODO This is internal, make it private as soon as possible.
-gpointer
-retro_core_get_module_video_refresh_cb (RetroCore *self)
-{
-  return video_refresh_cb;
-}
-
 static void
 audio_sample_cb (gint16 left,
                  gint16 right)