Merge branch 'bpf-btf' into iproute2-next

Daniel Borkmann  says:

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Main part of this set is to: i) avoid strict af_alg kernel dependency,
ii) add loader support for bpf to bpf calls and iii) add btf loader
support with an option to annotate maps. For details please see the
individual patches. Thanks!

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Signed-off-by: David Ahern <dsahern@gmail.com>