tools headers: Synchronize perf_event.h header

To get the changes in the 085b3062 ("perf/core: Add
PERF_AUX_FLAG_COLLISION to report colliding samples") commit, that will
be eventually used by perf to handle the ARM SPE architecture.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/n/tip-178ohv0oy0csq3kzfdk8ky4n@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>