At some point the name of the doc-tool script changed and we stopped
patching up the shabang line. The new one is just scripts/bpf_doc.py.
(cherry picked from commit 8997f8cc709f6d1801a23de80a7954e48116d1b2)
I needed some other bpf-related tools located in the kernel source tree,
so I hijacked the bpftool package, renamed it to bpftools and added
those programs.