perf test: check if cpu_map__new() return NULL

It looks like we should check if cpus is NULL after

	cpus = cpu_map__new(NULL);

in test__open_syscall_event_on_all_cpus().

LKML-Reference: <20110114230050.GA7011@localhost>
Signed-off-by: NHan Pingtian <phan@redhat.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-test.c

@@ -347,9 +347,9 @@ static int test__open_syscall_event_on_all_cpus(void)
 	}
 
 	cpus = cpu_map__new(NULL);
-	if (threads == NULL) {
-		pr_debug("thread_map__new\n");
-		return -1;
+	if (cpus == NULL) {
+		pr_debug("cpu_map__new\n");
+		goto out_thread_map_delete;
 	}