reproduce:
        git remote add masahiroy-kbuild https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
        git fetch masahiroy-kbuild fixes
        git checkout masahiroy-kbuild/fixes
        b4 shazam https://lore.kernel.org/r/20240516133009.20224-7-lhruska@suse.cz
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf