tools headers UAPI: Update tools's copy of linux/perf_event.h

To get the changes in:

  6546b19f ("perf/core: Add PERF_SAMPLE_CGROUP feature")
  96aaab68 ("perf/core: Add PERF_RECORD_CGROUP event")

This silences this perf tools build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/perf_event.h' differs from latest version at 'include/uapi/linux/perf_event.h'
  diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h

This update is a prerequisite to adding support for the HW index of raw
branch records.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: http://lore.kernel.org/lkml/20200325124536.2800725-4-namhyung@kernel.org


[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>