Add Qt libs and headers

paho-mqtt3as-proxy/Qt/include/QtCore/q20memory.h

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+// Copyright (C) 2023 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 Q20MEMORY_H
+#define Q20MEMORY_H
+
+#include <QtCore/qtconfigmacros.h>
+
+#include <memory>
+#include <utility>
+
+#include <type_traits>
+
+//
+//  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
+
+// like std::construct_at (but not whitelisted for constexpr)
+namespace q20 {
+#ifdef __cpp_lib_constexpr_dynamic_alloc
+using std::construct_at;
+#else
+template <typename T,
+          typename... Args,
+          typename Enable = std::void_t<decltype(::new (std::declval<void *>()) T(std::declval<Args>()...))> >
+T *construct_at(T *ptr, Args && ... args)
+{
+    return ::new (const_cast<void *>(static_cast<const volatile void *>(ptr)))
+                                                                T(std::forward<Args>(args)...);
+}
+#endif // __cpp_lib_constexpr_dynamic_alloc
+} // namespace q20
+
+QT_END_NAMESPACE
+
+#endif /* Q20MEMORY_H */