GtkIconTheme: keep misplaced symbolics working
GtkIconTheme: keep misplaced symbolics working

Recent changes made it a breaking mistake to install symbolic icons
of the wrong size into a theme directory, or into the legacy unthemed
icon location.

Since this change affects many apps, do the extra work to keep these
icons working, but emit warnings, in the hope that this will lead to
cleaning up the mess over time.

jigpu/gtk,Lyude/gtk-,grubersjoe/adwaita,chergert/gtk,grubersjoe/adwaita,jigpu/gtk,Lyude/gtk-,chergert/gtk,ahodesuka/gtk,ahodesuka/gtk,jigpu/gtk,davidgumberg/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,Adamovskiy/gtk,jadahl/gtk,jessevdk/gtk,Lyude/gtk-,ahodesuka/gtk,ahodesuka/gtk,alexlarsson/gtk,chergert/gtk,jessevdk/gtk,davidgumberg/gtk,jadahl/gtk,jadahl/gtk,jigpu/gtk,grubersjoe/adwaita,jessevdk/gtk,Lyude/gtk-,grubersjoe/adwaita,grubersjoe/adwaita,chergert/gtk,alexlarsson/gtk,ahodesuka/gtk,Lyude/gtk-,grubersjoe/adwaita,chergert/gtk,jessevdk/gtk,alexlarsson/gtk,Adamovskiy/gtk,ahodesuka/gtk,Adamovskiy/gtk,Adamovskiy/gtk,grubersjoe/adwaita,davidgumberg/gtk,ahodesuka/gtk,jessevdk/gtk,jadahl/gtk,jadahl/gtk,Lyude/gtk-,davidgumberg/gtk,alexlarsson/gtk,jigpu/gtk,alexlarsson/gtk,davidgumberg/gtk,Adamovskiy/gtk,davidgumberg/gtk,Lyude/gtk-,jadahl/gtk,alexlarsson/gtk,jessevdk/gtk,davidgumberg/gtk,alexlarsson/gtk,Adamovskiy/gtk,Lyude/gtk-,davidgumberg/gtk,chergert/gtk,chergert/gtk,Adamovskiy/gtk,alexlarsson/gtk,jessevdk/gtk,jadahl/gtk,Adamovskiy/gtk,jigpu/gtk,grubersjoe/adwaita,jigpu/gtk,jigpu/gtk