perf tools: Release metric_events rblist

We don't release metric_events rblist, add the missing delete hook and
call the release before leaving cmd_stat.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200602214741.1218986-11-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-stat.c

@@ -2307,6 +2307,7 @@ out:
 
 	evlist__delete(evsel_list);
 
+	metricgroup__rblist_exit(&stat_config.metric_events);
 	runtime_stat_delete(&stat_config);
 
 	return status;