perf python: Set index error for invalid thread/cpu map items

Returning NULL for out of bound CPU or thread map items causes
internal errors. Fix by correctly setting the error to be an index
error.

Signed-off-by: Ian Rogers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/python.c

···
 {
 	struct pyrf_cpu_map *pcpus = (void *)obj;
 
-	if (i >= perf_cpu_map__nr(pcpus->cpus))
+	if (i >= perf_cpu_map__nr(pcpus->cpus)) {
+		PyErr_SetString(PyExc_IndexError, "Index out of range");
 		return NULL;
+	}
 
 	return Py_BuildValue("i", perf_cpu_map__cpu(pcpus->cpus, i).cpu);
 }
···
 {
 	struct pyrf_thread_map *pthreads = (void *)obj;
 
-	if (i >= perf_thread_map__nr(pthreads->threads))
+	if (i >= perf_thread_map__nr(pthreads->threads)) {
+		PyErr_SetString(PyExc_IndexError, "Index out of range");
 		return NULL;
+	}
 
 	return Py_BuildValue("i", perf_thread_map__pid(pthreads->threads, i));
 }