tools lib traceevent: Add retrieval of preempt count and latency flags

Add a way to retrieve the preempt count as well as the latency flags from a
pevent_record.

  int pevent_data_preempt_count(pevent, record);

returns the preempt count of a record.

  int pevent_data_flags(pevent, record);

returns the latency flags for a record.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20161122113158.03a010a8@gandalf.local.home


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