added nohalo.c
added nohalo.c

leiyangyou/libvips,mcanthony/libvips,lovell/libvips,wishabi/libvips,mcanthony/libvips,jcupitt/libvips,lovell/libvips,wishabi/libvips,jcupitt/libvips,wishabi/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips,leiyangyou/libvips,jcupitt/libvips,wishabi/libvips,leiyangyou/libvips,leiyangyou/libvips,mcanthony/libvips,mcanthony/libvips