perf sched timehist: Handle zero sample->tid properly

perf sched timehist: Handle zero sample->tid properly

Sometimes samples have tid of 0 but non-0 pid.  It ends up having a new
thread of 0 tid/pid (instead of referring idle task) since tid is used
to search matching task.  But I guess it's wrong to use 0 as a tid when
pid is set.  This patch uses tid only if it has a non-zero value or same
as pid (of 0).

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161206034010.6499-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>