perf tools: Use tid for finding thread

I believe that passing pid (instead of tid) as the 3rd arg of the
machine__find*_thread() was to find a main thread so that it can
search proper map group for symbols.  However with the map sharing
patch applied, it now can do it in any thread.

It fixes a bug when each thread has different name, it only reports a
main thread for samples in other threads.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: David Ahern <dsahern@gmail.com>
Acked-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1399856202-26221-1-git-send-email-namhyung@kernel.org


Signed-off-by: Jiri Olsa <jolsa@kernel.org>