IconTheme: Clear caches when reloading theme
IconTheme: Clear caches when reloading theme

When we're reloading the theme in ensure_valid_themes (due to noticing
that a theme dir has changed) we need to also clear the icon cache
as it will not be valid for the new theme.

We already do this in do_theme_change(), but ensure_valid_themes()
was missing this.

https://bugzilla.gnome.org/show_bug.cgi?id=702598

grubersjoe/adwaita,davidgumberg/gtk,jadahl/gtk,davidgumberg/gtk,chergert/gtk,chergert/gtk,jigpu/gtk,jigpu/gtk,grubersjoe/adwaita,msteinert/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,ebassi/gtk,ahodesuka/gtk,davidgumberg/gtk,Adamovskiy/gtk,bratsche/gtk-,Sidnioulz/SandboxGtk,Adamovskiy/gtk,jigpu/gtk,Adamovskiy/gtk,Adamovskiy/gtk,alexlarsson/gtk,jessevdk/gtk,chergert/gtk,alexlarsson/gtk,chergert/gtk,davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,jessevdk/gtk,Adamovskiy/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,chergert/gtk,jessevdk/gtk,Adamovskiy/gtk,msteinert/gtk,Lyude/gtk-,msteinert/gtk,jadahl/gtk,ebassi/gtk,ebassi/gtk,ahodesuka/gtk,ebassi/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,Lyude/gtk-,davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,alexlarsson/gtk,chergert/gtk,alexlarsson/gtk,jessevdk/gtk,jadahl/gtk,bratsche/gtk-,ahodesuka/gtk,jessevdk/gtk,jigpu/gtk,ahodesuka/gtk,Lyude/gtk-,chergert/gtk,Sidnioulz/SandboxGtk,jigpu/gtk,Sidnioulz/SandboxGtk,jessevdk/gtk,msteinert/gtk,grubersjoe/adwaita,davidgumberg/gtk,msteinert/gtk,Lyude/gtk-,chergert/gtk,Adamovskiy/gtk,msteinert/gtk,jigpu/gtk,davidgumberg/gtk,bratsche/gtk-,jigpu/gtk,grubersjoe/adwaita,ebassi/gtk,grubersjoe/adwaita,alexlarsson/gtk,ahodesuka/gtk,ebassi/gtk,bratsche/gtk-,jadahl/gtk,ahodesuka/gtk,alexlarsson/gtk,jessevdk/gtk,jadahl/gtk,bratsche/gtk-,grubersjoe/adwaita,ahodesuka/gtk,grubersjoe/adwaita,Lyude/gtk-,bratsche/gtk-,Lyude/gtk-,Adamovskiy/gtk,grubersjoe/adwaita,ahodesuka/gtk,jadahl/gtk,Lyude/gtk-