perf parse-events: Fix evsel allocation failure

If evsel__new_idx() returns NULL, the function currently jumps to label
'out_err'.  Here, references to `cpus` and `pmu_cpus` are dropped.
Also, resources held by evsel->name and evsel->metric_id are freed.

But if evsel__new_idx() returns NULL, it can lead to NULL pointer
dereference.

Fixes: cd63c22 ("perf parse-events: Minor __add_event refactoring")
Signed-off-by: Faisal Bukhari <faisalbukhari523@gmail.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: Faisal-523

tools/perf/util/parse-events.c

@@ -251,8 +251,11 @@ __add_event(struct list_head *list, int *idx,
 		event_attr_init(attr);
 
 	evsel = evsel__new_idx(attr, *idx);
-	if (!evsel)
-		goto out_err;
+	if (!evsel) {
+		perf_cpu_map__put(cpus);
+		perf_cpu_map__put(pmu_cpus);
+		return NULL;
+	}
 
 	if (name) {
 		evsel->name = strdup(name);