Fix macros and remove the unintended exposed interface

Author: SidneyCogdill

zmq_async.hpp

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "zmq_addon.hpp"
+#include <zmq_addon.hpp>
 #include <boost/asio/any_io_executor.hpp>
 #include <boost/system/detail/error_code.hpp>
 #include <stdexcept>
@@ -11,17 +11,15 @@
 #if !defined(ZMQ_CPP20) && defined(CPPZMQ_ENABLE_CORRAL_COROUTINE)
 #error "Coroutine support enabled with a C++ standard lower than C++20"
 #endif
-#if defined(CPPZMQ_ENABLE_CORRAL_COROUTINE)
+#if defined(ZMQ_CPP20) && defined(CPPZMQ_ENABLE_CORRAL_COROUTINE)
+// As coroutine support is only avaiable for C++20 and upward,
+// there is no point in using the ZMQ_XXX macros for compatibility.
+// Everything that's available in C++20 can be used here (e.g. inline, noexcept).
+
 #include <corral/Task.h>
 #include <boost/asio/posix/stream_descriptor.hpp>
 #include <boost/asio/windows/stream_handle.hpp>
-#endif
 
-
-#ifdef ZMQ_CPP20
-// As coroutine support is only avaiable for C++20 and upward,
-// there is no point in using the ZMQ_XXX macros for compatibility.
-// Everything that's available in C++20 can be used here (e.g. inline, noexcept).
 namespace zmq
 {
 
@@ -92,10 +90,6 @@ struct [[nodiscard]] async_send_awaitable_t
     {
     }
 
-  public /* interface */:
-    inline auto enable_flag(zmq::send_flags flag) { m_flags = m_flags | flag; }
-    inline auto disable_flag(zmq::send_flags flag) { m_flags = m_flags & (~flag); }
-
   public /* awaitable */:
     ///
     /// \brief An optimization which avoids suspending the coroutine if it isn't necessary.