message: protect xmap when assigning values in set_u64c()
diff: @@ -55,7 +55,8 @@ void CXVersionMessage::set_u64c(const uint64_t key, const uint64_t val)
  std::vector<uint8_t> vec;
  vec.insert(vec.begin(), s.begin(), s.end());
  - xmap[key] = vec;
  +
  LOCK(cacheProtector);
  + xmap[key] = vec;
  cache_u64c[key] = val;
  }
  