Add Qt libs and headers

paho-mqtt3as-proxy/Qt/include/QtCore/q23functional.h

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+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+#ifndef Q23FUNCTIONAL_H
+#define Q23FUNCTIONAL_H
+
+#include <QtCore/qglobal.h>
+#include <QtCore/q20functional.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. Types and functions defined in this
+// file can reliably be replaced by their std counterparts, once available.
+// You may use these definitions in your own code, but be aware that we
+// will remove them once Qt depends on the C++ version that supports
+// them in namespace std. There will be NO deprecation warning, the
+// definitions will JUST go away.
+//
+// If you can't agree to these terms, don't use these definitions!
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+namespace q23 {
+// like std::invoke_r
+#ifdef __cpp_lib_invoke_r
+using std::invoke_r;
+#else
+template <typename R, typename F, typename...Args>
+constexpr
+std::enable_if_t<std::is_invocable_r_v<R, F, Args...>, R>
+invoke_r(F&& f, Args&&... args)
+    noexcept(std::is_nothrow_invocable_r_v<R, F, Args...>)
+{
+    // ### use q20::invoke for a constexpr std::invoke
+    if constexpr (std::is_void_v<R>)
+        std::invoke(std::forward<F>(f), std::forward<Args>(args)...);
+    else
+        return std::invoke(std::forward<F>(f), std::forward<Args>(args)...);
+}
+#endif // __cpp_lib_invoke_r
+} // namespace q23
+
+QT_END_NAMESPACE
+
+#endif /* Q23FUNCTIONAL_H */