Add clean target for data/ so make clean works again
Add clean target for data/ so make clean works again

sir-murray/wayland,mchalupa/weston,Fantu/compositor-spice,udoprog/weston,eyolfson/weston,sir-murray/weston,jonnylamb/weston,Fantu/compositor-spice,Gnurou/weston,Tarnyko/weston-xdg_surface_present,sir-murray/wayland,abooij/wayland,tulcod/wayland,kwm81/weston,kwm81/weston,mchalupa/wayland,Fantu/compositor-spice,sir-murray/wayland,bitfactor/wayland,jonnylamb/weston,abooij/wayland,eyolfson/wayland,xorgy/weston,mchalupa/weston,bitfactor/wayland,bitfactor/wayland,giucam/weston,krezovic/weston,mchalupa/wayland,xorgy/weston,sir-murray/weston,giucam/weston,eyolfson/wayland,eyolfson/weston,mchalupa/wayland,udoprog/weston,eyolfson/wayland,tulcod/wayland,krezovic/weston,abooij/wayland,Gnurou/weston,Tarnyko/weston-xdg_surface_present,tulcod/wayland