fixes the exit-code error on osx builds.

include/boost/process/v2/detail/process_handle_windows.hpp

@@ -308,7 +308,7 @@ struct basic_process_handle_win
  public:
     template<BOOST_PROCESS_V2_COMPLETION_TOKEN_FOR(void(error_code, native_exit_code_type))
              WaitHandler = net::default_completion_token_t<executor_type>>
-    auto async_wait(WaitHandler &&handler = net::default_completion_token_t<executor_type>())
+    auto async_wait(WaitHandler &&handler = default_completion_token_t<executor_type>())
         -> decltype(net::async_compose<WaitHandler, void(error_code, native_exit_code_type)>(
                     async_wait_op_{handle_}, handler, handle_))
     {

test/v1/exit_code.cpp

@@ -148,12 +148,17 @@ BOOST_AUTO_TEST_CASE(async_nowait, *boost::unit_test::timeout(10))
     boost::asio::io_context io_context;
     bp::child c(
             master_test_suite().argv[1],
-            "test", "--exit-code", "221",
+            "test", "--exit-code", "121",
             ec,
             bp::on_exit=[](int exit_code, std::error_code) mutable {},
             io_context
     );
     BOOST_REQUIRE(!ec);
-    io_context.run_for(std::chrono::milliseconds(100));
-    BOOST_CHECK_EQUAL(221, c.exit_code());
+    while (c.running())
+    {
+      io_context.run_for(std::chrono::milliseconds(10));
+      io_context.restart();
+    }
+
+    BOOST_CHECK_EQUAL(121, c.exit_code());
 }