Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/stddef.h

@@ -0,0 +1,53 @@
+// -*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__need_ptrdiff_t) || defined(__need_size_t) || \
+    defined(__need_wchar_t) || defined(__need_NULL) || defined(__need_wint_t)
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#include_next <stddef.h>
+
+#elif !defined(_LIBCPP_STDDEF_H)
+#define _LIBCPP_STDDEF_H
+
+/*
+    stddef.h synopsis
+
+Macros:
+
+    offsetof(type,member-designator)
+    NULL
+
+Types:
+
+    ptrdiff_t
+    size_t
+    max_align_t // C++11
+    nullptr_t
+
+*/
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#  if __has_include_next(<stddef.h>)
+#    include_next <stddef.h>
+#  endif
+
+#ifdef __cplusplus
+    typedef decltype(nullptr) nullptr_t;
+#endif
+
+#endif // _LIBCPP_STDDEF_H