Merge branch 'resolve_btfids'

Jiri Olsa says:

====================
This patchset adds:
  - support to generate BTF ID lists that are resolved during
    kernel linking and usable within kernel code with following
    macros:

      BTF_ID_LIST(bpf_skb_output_btf_ids)
      BTF_ID(struct, sk_buff)

    and access it in kernel code via:
      extern u32 bpf_skb_output_btf_ids[];

  - resolve_btfids tool that scans elf object for .BTF_ids
    section and resolves its symbols with BTF ID values
  - resolving of bpf_ctx_convert struct and several other
    objects with BTF_ID_LIST

v7 changes:
  - added more acks [Andrii]
  - added some name-conflicting entries and fixed resolve_btfids
    to process them properly [Andrii]
  - changed bpf_get_task_stack_proto to use BTF_IDS_LIST/BTF_ID
    macros [Andrii]
  - fixed selftest build for resolve_btfids test
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>