Backport Neon patches regarding background colour and CPU usage.
- [GTK3.16+] gtk_widget_override_background_color is deprecated.
- [GTK3] Eclipse IDE consumes CPU when idle
- [GTK] Empty repositories view links have white backgrounds
- Resolves: rhbz#1294697, rhbz#1269892
- ebz#483096, ebz#484696, ebz#484729