Make it possible to build bpftool without libbfd. libbfd and libopcodes are typically provided in dev/dbg packages (binutils-dev in debian) which we usually don't have installed on the fleet machines and we'd like a way to have bpftool version that works without installing any additional packages. This excludes support for disassembling jit-ted code and prints an error if the user tries to use these features. Tested by: cat > FEATURES_DUMP.bpftool <<EOF feature-libbfd=0 feature-disassembler-four-args=1 feature-reallocarray=0 feature-libelf=1 feature-libelf-mmap=1 feature-bpf=1 EOF FEATURES_DUMP=$PWD/FEATURES_DUMP.bpftool make ldd bpftool | grep libbfd Signed-off-by: Stanislav Fomichev <sdf@google.com> Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>