Release Cosmopolitan v3.6.0

This release is an atomic upgrade to GCC 14.1.0 with C23 and C++23

third_party/libcxx/__fwd/mdspan.h

@@ -0,0 +1,57 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___MDSPAN_LAYOUTS_H
+#define _LIBCPP___MDSPAN_LAYOUTS_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+// Layout policy with a mapping which corresponds to FORTRAN-style array layouts
+struct layout_left {
+  template <class _Extents>
+  class mapping;
+};
+
+// Layout policy with a mapping which corresponds to C-style array layouts
+struct layout_right {
+  template <class _Extents>
+  class mapping;
+};
+
+// Layout policy with a unique mapping where strides are arbitrary
+struct layout_stride {
+  template <class _Extents>
+  class mapping;
+};
+
+#endif // _LIBCPP_STD_VER >= 23
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___MDSPAN_LAYOUTS_H