lib/sodium/Arithmetic: new header with <sodium/utils.h> wrappers

Author: MaxKellermann

src/lib/sodium/Arithmetic.hxx

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <max.kellermann@gmail.com>
+
+#pragma once
+
+#include <sodium/utils.h>
+
+#include <cstddef> // for std::byte
+#include <span>
+
+inline void
+sodium_increment(std::span<std::byte> n) noexcept
+{
+	sodium_increment(reinterpret_cast<unsigned char *>(n.data()), n.size());
+}