Add two new helper functions to trace_helpers that supports polling
multiple perf file descriptors for events. These are used to the XDP
perf_event_output example, which needs to work with one perf fd per CPU.
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NToke Høiland-Jørgensen <toke@toke.dk>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>