Merge branch 'bpf: Fix cookie values for kprobe multi'

Jiri Olsa says:

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

hi,
there's bug in kprobe_multi link that makes cookies misplaced when
using symbols to attach. The reason is that we sort symbols by name
but not adjacent cookie values. Current test did not find it because
bpf_fentry_test* are already sorted by name.

v3 changes:
  - fixed kprobe_multi bench test to filter out invalid entries
    from available_filter_functions

v2 changes:
  - rebased on top of bpf/master
  - checking if cookies are defined later in swap function [Andrii]
  - added acks

thanks,
jirka
====================

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