message: Respect DUCKDB_NO_THREADS config
diff: #include "duckdb/transaction/transaction_manager.hpp"
  #include "duckdb/main/connection_manager.hpp"
  -#include <thread> // for hardware_concurrency()
  +#ifndef DUCKDB_NO_THREADS
  +#include "duckdb/common/thread.hpp"
  +#endif
  namespace duckdb {
  @@ -177,7 +179,11 @@ void DatabaseInstance::Configure(DBConfig &new_config) {
  config.maximum_memory = new_config.maximum_memory;
  }
  if (new_config.maximum_threads == (idx_t)-1) {
  +#ifndef DUCKDB_NO_THREADS
  config.maximum_threads = std::thread::hardware_concurrency();
  +#else
  + config.maximum_threads = 1;
  +#endif
  } else {
  config.maximum_threads = new_config.maximum_threads;
  }
  