reproduce (this is a W=1 build):
        # https://github.com/jimc/linux/commit/a3f35a330ec694a21578ef9d439e502c80e3e227
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc dd-shrink-go
        git checkout a3f35a330ec694a21578ef9d439e502c80e3e227
        # apt-get install llvm-dev

        # save the config file
        make W=1 ARCH=i386 olddefconfig
        make W=1 ARCH=i386 
        make W=1 headers_install
        make W=1 -C tools/testing/selftests