message: Issue External Window Sorting
  Move mutex to where it is actually needed.
diff: @@ -412,10 +412,11 @@ void WindowLocalSinkState::Sink(DataChunk &input_chunk, WindowGlobalSinkState &g
  }
  void WindowLocalSinkState::Combine(WindowGlobalSinkState &gstate) {
  - lock_guard<mutex> glock(gstate.lock);
  // OVER()
  if (over_chunk.ColumnCount() == 0) {
  + // Only one partition again, so need a global lock.
  + lock_guard<mutex> glock(gstate.lock);
  if (gstate.rows) {
  if (rows) {
  gstate.rows->Merge(*rows);
  