Description of problem:
The output of:
  trace-cmd report -w -F 'sched_switch,sched_wakeup'
no longer works correctly, as of trace-cmd version 2.4.2

In the 2.4.2 version, it reported the Latency for each sched_switch. 
It also reported a nice summary at the end for Average wakeup latency,
for Maximum Latency, and for Minimum Latency.

None of that is reported in newer versions of trace-cmd.
Those latency values are valuable for diagnosing scheduler related
issues.

RHEL 7.* uses versions newer than 2.4.2, which do not work correctly.



How reproducible:


Steps to Reproduce:
1. trace-cmd record -e all   // And then hit ctrl-c immediately
                             // for a small trace.dat file
2.trace-cmd report -w -F 'sched_switch,sched_wakeup'


Expected results:
Each "sched_switch" line would report the individual Latency value.  See these two sched_switch lines:

          <idle>-0     [073]  3332.027239: sched_switch:         prev_comm=swapper/73 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=5581 next_prio=120 Latency: 6.565 usecs
          <idle>-0     [026]  3332.027241: sched_switch:         prev_comm=swapper/26 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=trace-cmd next_pid=5577 next_prio=120 Latency: 8.630 usecs

And then at the end of the output, the summary would look like this:

   Average wakeup latency: 10.324 usecs
   Maximum Latency: 214.505 usecs at timestamp: 3332.869763
   Minimum Latency: 0.432 usecs at timestamp: 3332.534240

   RT task timings:

   Average wakeup latency: 8.258 usecs
   Maximum Latency: 18.836 usecs at timestamp: 3332.027711
   Minimum Latency: 4.599 usecs at timestamp: 3332.432522


Actual results:
After trace-cmd version 2.4.2, the individual Latencies for the sched_switch
entries are missing, as is the summary of Latency information at the
end of the report.


Additional info: