message: fix sporadic crashes
  Addresses
diff: @@ -870,7 +870,7 @@ private:
  PERF_TOPDOWN_RETIRING_POS = PERF_TOPDOWN_SLOTS_POS + 4
  };
  - std::unordered_map<int, int> perfTopDownPos;
  + std::array<int, (PERF_TOPDOWN_RETIRING_POS + 1)> perfTopDownPos;
  enum {
  PERF_GROUP_LEADER_COUNTER = PERF_INST_RETIRED_POS,
  