build-sys: Remove unused conditional
build-sys: Remove unused conditional

flexVDI/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,flexVDI/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,fgouget/spice-gtk,fgouget/spice-gtk