[libgd] (4 commits) Non-fast-forward update to branch wip/ernestask/gtk4

[Ernestas Kulik <ernestask src gnome org>]

The branch 'wip/ernestask/gtk4' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  9255b02... notification: remove visibility_notify_event override
  5f891ff... notification: use gtk_widget_get_allocated_height()
  c7352bc... notification: default to being invisible
  e11cffb... toggle-pixbuf-renderer: copy gtk_paint_spinner() from GTK+

Commits added to the branch:

  c3dbe3e... notification: remove visibility_notify_event override
  ccaa2bf... notification: use gtk_widget_get_allocated_height()
  bee20be... notification: default to being invisible
  ec3e623... toggle-pixbuf-renderer: copy gtk_paint_spinner() from GTK+