Merge branch 'perf tools: Fix prologue generation'

Jiri Olsa says:

====================

hi,
sending change we discussed some time ago [1] to get rid of
some deprecated functions we use in perf prologue code.

Despite the gloomy discussion I think the final code does
not look that bad ;-)

This patchset removes following libbpf functions from perf:
  bpf_program__set_prep
  bpf_program__nth_fd
  struct bpf_prog_prep_result

v5 changes:
  - squashed patches together so we don't break bisection [Arnaldo]

v4 changes:
  - fix typo [Andrii]

v3 changes:
  - removed R0/R1 zero init in libbpf_prog_prepare_load_fn,
    because it's not needed [Andrii]
  - rebased/post on top of bpf-next/master which now has
    all the needed perf/core changes

v2 changes:
  - use fallback section prog handler, so we don't need to
    use section prefix [Andrii]
  - realloc prog->insns array in bpf_program__set_insns [Andrii]
  - squash patch 1 from previous version with
    bpf_program__set_insns change [Daniel]
  - patch 3 already merged [Arnaldo]
  - added more comments

thanks,
jirka

[1] https://lore.kernel.org/bpf/CAEf4BzaiBO3_617kkXZdYJ8hS8YF--ZLgapNbgeeEJ-pY0H88g@mail.gmail.com/
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>