Merge branch 'libbpf: streamline netlink-based XDP APIs'

Andrii Nakryiko says:

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Revamp existing low-level XDP APIs provided by libbpf to follow more
consistent naming (new APIs follow bpf_tc_xxx() approach where it makes
sense) and be extensible without ABI breakages (OPTS-based). See patch #1 for
details, remaining patches switch bpftool, selftests/bpf and samples/bpf to
new APIs.
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>