perf python: Convert tracepoint.py example to python3

Convert the tracepoint.py file to python3 as many of the files in
tools/perf are already written in python3.

Committer testing:

# export PYTHONPATH=/tmp/build/perf/python/
# python3 ~acme/git/perf/tools/perf/python/tracepoint.py | head
time 67394457376909 prev_comm=swapper/12 prev_pid=0 prev_prio=120 prev_state=0x0 ==> next_comm=gnome-terminal- next_pid=3313 next_prio=120
time 67394457807669 prev_comm=python3 prev_pid=1485930 prev_prio=120 prev_state=0x1 ==> next_comm=swapper/13 next_pid=0 next_prio=120
time 67394457811859 prev_comm=swapper/13 prev_pid=0 prev_prio=120 prev_state=0x0 ==> next_comm=python3 next_pid=1485930 next_prio=120
time 67394457824929 prev_comm=python3 prev_pid=1485930 prev_prio=120 prev_state=0x1 ==> next_comm=swapper/13 next_pid=0 next_prio=120
time 67394457831899 prev_comm=swapper/13 prev_pid=0 prev_prio=120 prev_state=0x0 ==> next_comm=python3 next_pid=1485930 next_prio=120
time 67394457842299 prev_comm=python3 prev_pid=1485930 prev_prio=120 prev_state=0x1 ==> next_comm=swapper/13 next_pid=0 next_prio=120
time 67394457844179 prev_comm=swapper/13 prev_pid=0 prev_prio=120 prev_state=0x0 ==> next_comm=python3 next_pid=1485930 next_prio=120
time 67394457853879 prev_comm=python3 prev_pid=1485930 prev_prio=120 prev_state=0x1 ==> next_comm=swapper/13 next_pid=0 next_prio=120
time 67394457856339 prev_comm=swapper/13 prev_pid=0 prev_prio=120 prev_state=0x0 ==> next_comm=python3 next_pid=1485930 next_prio=120
time 67394457865659 prev_comm=python3 prev_pid=1485930 prev_prio=120 prev_state=0x1 ==> next_comm=swapper/13 next_pid=0 next_prio=120
Traceback (most recent call last):
File "/var/home/acme/git/perf/tools/perf/python/tracepoint.py", line 48, in <module>
main()
File "/var/home/acme/git/perf/tools/perf/python/tracepoint.py", line 37, in main
print("time %u prev_comm=%s prev_pid=%d prev_prio=%d prev_state=0x%x ==> next_comm=%s next_pid=%d next_prio=%d" % (
BrokenPipeError: [Errno 32] Broken pipe
#

Signed-off-by: Tanu M <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/linux-perf-users/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/python/tracepoint.py

···
             if not isinstance(event, perf.sample_event):
                 continue
 
-            print "time %u prev_comm=%s prev_pid=%d prev_prio=%d prev_state=0x%x ==> next_comm=%s next_pid=%d next_prio=%d" % (
+            print("time %u prev_comm=%s prev_pid=%d prev_prio=%d prev_state=0x%x ==> next_comm=%s next_pid=%d next_prio=%d" % (
                    event.sample_time,
                    event.prev_comm,
                    event.prev_pid,
···
                    event.prev_state,
                    event.next_comm,
                    event.next_pid,
-                   event.next_prio)
+                   event.next_prio))
 
 if __name__ == '__main__':
     main()