Fix memory leak in magick free
Fix memory leak in magick free

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