gdk/Makefile.am: Fix MSVC Project Generation
gdk/Makefile.am: Fix MSVC Project Generation

We need to account for the sources that moved to gdk/deprecated/, so the
slashes must be converted here.

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