perf machine: Carve up event processing specific from perf_tool

The perf_tool vtable expects methods that receive perf_tool and
perf_sample entries, but for tools not interested in doing any special
processing on non PERF_RECORD_SAMPLE events, like 'perf top', and for
those not using perf_session, like 'perf trace', they were using
perf_event__process passing tool and sample paramenters that were just
not used.

Provide 'machine' methods for this purpose and make the perf_event
ones use them.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ot9cc6mt025o8kbngzckcrx9@git.kernel.org


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