message: Reduce watermark console spew.
diff: @@ -128,8 +128,10 @@ AtomicFreeList::AtomicFreeList(void* begin, void* end,
  TrackingPolicy::HighWatermark::~HighWatermark() noexcept {
  size_t wm = mHighWaterMark;
  size_t wmpct = wm / (mSize / 100);
  + if (wmpct > 80) {
  slog.d << mName << " arena: High watermark "
  << wm / 1024 << " KiB (" << wmpct << "%)" << io::endl;
  }
  +}
  } // namespace utils
  