fix write ICC profile to webp
fix write ICC profile to webp

ooops, a typo broke ICC profile write to webp 18 days ago

thanks augustocdias

see https://github.com/libvips/libvips/issues/1767

lovell/libvips,lovell/libvips,jcupitt/libvips,jcupitt/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips,lovell/libvips