reproduce (this is a W=1 build):
        git checkout next-20251029
        b4 shazam https://lore.kernel.org/r/20251029173828.3682-7-david.laight.linux@gmail.com

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash lib/math/