screen-cast: Track and always record cursors

Always force-track the cursor position (so that the X11 backend can keep
it up to date), and if the cursor wasn't part of the sampled
framebuffer when reading pixels into CPU memory, draw it in an extra
pass using cairo after the fact. The cairo based cursor painting only
happens on the X11 backend, as we otherwise inhibit the hw cursor.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1391

src/backends/meta-cursor-renderer.c

@@ -409,6 +409,18 @@ meta_cursor_renderer_get_cursor (MetaCursorRenderer *renderer)
   return priv->displayed_cursor;
 }
 
+gboolean
+meta_cursor_renderer_is_overlay_visible (MetaCursorRenderer *renderer)
+{
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+
+  if (!priv->stage_overlay)
+    return FALSE;
+
+  return meta_overlay_is_visible (priv->stage_overlay);
+}
+
 void
 meta_cursor_renderer_add_hw_cursor_inhibitor (MetaCursorRenderer    *renderer,
                                               MetaHwCursorInhibitor *inhibitor)