Fix missing threadpool changes in patch

Author: IsaacWarren

recipe/patches/0004-Bodo-Changes.patch

@@ -233,3 +233,54 @@ index 50310577f1..0b5162f25f 100644
  };
 
  /// \brief ScannerBuilder is a factory class to construct a Scanner. It is used
+diff --git a/cpp/src/arrow/util/thread_pool.h b/cpp/src/arrow/util/thread_pool.h
+index cd32781aed..a8935d751a 100644
+--- a/cpp/src/arrow/util/thread_pool.h
++++ b/cpp/src/arrow/util/thread_pool.h
+@@ -20,6 +20,7 @@
+ #include <cstdint>
+ #include <memory>
+ #include <queue>
++#include <thread>
+ #include <type_traits>
+ #include <unordered_set>
+ #include <utility>
+@@ -591,6 +592,21 @@ typename Fut::SyncType RunSynchronously(FnOnce<Fut(Executor*)> get_future,
+   }
+ }
+ 
++template <typename T>
++Iterator<T> IterateSynchronously(
++    FnOnce<Result<std::function<Future<T>()>>(Executor*)> get_gen, bool use_threads,
++    Executor* executor) {
++  if (use_threads) {
++    auto maybe_gen = std::move(get_gen)(executor);
++    if (!maybe_gen.ok()) {
++      return MakeErrorIterator<T>(maybe_gen.status());
++    }
++    return MakeGeneratorIterator(*maybe_gen);
++  } else {
++    return SerialExecutor::IterateGenerator(std::move(get_gen));
++  }
++}
++
+ /// \brief Potentially iterate an async generator serially (if use_threads is false)
+ /// \see IterateGenerator
+ ///
+@@ -605,15 +621,7 @@ typename Fut::SyncType RunSynchronously(FnOnce<Fut(Executor*)> get_future,
+ template <typename T>
+ Iterator<T> IterateSynchronously(
+     FnOnce<Result<std::function<Future<T>()>>(Executor*)> get_gen, bool use_threads) {
+-  if (use_threads) {
+-    auto maybe_gen = std::move(get_gen)(GetCpuThreadPool());
+-    if (!maybe_gen.ok()) {
+-      return MakeErrorIterator<T>(maybe_gen.status());
+-    }
+-    return MakeGeneratorIterator(*maybe_gen);
+-  } else {
+-    return SerialExecutor::IterateGenerator(std::move(get_gen));
+-  }
++  return IterateSynchronously(std::move(get_gen), use_threads, GetCpuThreadPool());
+ }
+ 
+ }  // namespace internal