better vips7 option parsing
better vips7 option parsing

valgrind could complain about the previous one

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