build: Fix srcdir != builddir with wayland-client-protocol.h
build: Fix srcdir != builddir with wayland-client-protocol.h

In the gnome-ostree model builddir contains all generated files not in
git (unless the build system explicitly overrides that).  Here the
wayland-client-protocol.h was in $(builddir)/wayland, so we need to
find it using our already extant -I$(top_builddir)/gdk, rather than
relying on same-directory lookup.

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