perf sched: Cleanup, remove unused variables in map_switch_event()

In map_switch_event(), we don't care the previous process currently,
this patch remove the infomation we get but not used.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/1400218625-14613-1-git-send-email-yangds.fnst@cn.fujitsu.com
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

tools/perf/builtin-sched.c

@@ -1266,9 +1266,8 @@ static int process_sched_wakeup_event(struct perf_tool *tool,
 static int map_switch_event(struct perf_sched *sched, struct perf_evsel *evsel,
 			    struct perf_sample *sample, struct machine *machine)
 {
-	const u32 prev_pid = perf_evsel__intval(evsel, sample, "prev_pid"),
-		  next_pid = perf_evsel__intval(evsel, sample, "next_pid");
-	struct thread *sched_out __maybe_unused, *sched_in;
+	const u32 next_pid = perf_evsel__intval(evsel, sample, "next_pid");
+	struct thread *sched_in;
 	int new_shortname;
 	u64 timestamp0, timestamp = sample->time;
 	s64 delta;
@@ -1291,7 +1290,6 @@ static int map_switch_event(struct perf_sched *sched, struct perf_evsel *evsel,
 		return -1;
 	}
 
-	sched_out = machine__findnew_thread(machine, 0, prev_pid);
 	sched_in = machine__findnew_thread(machine, 0, next_pid);
 
 	sched->curr_thread[this_cpu] = sched_in;