perf trace: Drop thread refcount in trace__event_handler()

We must pair:

   thread = machine__findnew_thread();

with thread__put(thread). Fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: c4191e55 ("perf trace: Show comm and tid for tracepoint events")
Link: https://lkml.kernel.org/n/tip-dkxsb8cwg87rmkrzrbns1o4z@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -2152,8 +2152,8 @@ static int trace__event_handler(struct trace *trace, struct perf_evsel *evsel,
 		trace__fprintf_callchain(trace, sample);
 	else if (callchain_ret < 0)
 		pr_err("Problem processing %s callchain, skipping...\n", perf_evsel__name(evsel));
-	thread__put(thread);
 out:
+	thread__put(thread);
 	return 0;
 }