Add kernel AUX area sampling definitions, which brings perf_event.h into
line with the kernel version.

New sample type PERF_SAMPLE_AUX requests a sample of the AUX area
buffer.  New perf_event_attr member 'aux_sample_size' specifies the
desired size of the sample.

Also add support for parsing samples containing AUX area data i.e.
PERF_SAMPLE_AUX.

Committer notes:

I squashed the first two patches in this series to avoid breaking
automatic bisection, i.e. after applying only the original first patch
in this series we would have:

  # perf test -v parsing
  26: Sample parsing                                        :
  --- start ---
  test child forked, pid 17018
  sample format has changed, some new PERF_SAMPLE_ bit was introduced - test needs updating
  test child finished with -1
  ---- end ----
  Sample parsing: FAILED!
  #

With the two paches combined:

  # perf test parsing
  26: Sample parsing                                        : Ok
  #
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20191115124225.5247-3-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>