Import Mbed OS hard-float snapshot

UNITTESTS/target_h/platform/cxxsupport/mstd_utility

@@ -0,0 +1,75 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2019 ARM Limited
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MSTD_UTILITY_
+#define MSTD_UTILITY_
+
+/* <mstd_utility>
+ *
+ * - includes toolchain's <utility>
+ * - For ARM C 5, standard C++11/14 features:
+ *   - include <initializer_list>
+ *   - std::move, std::forward, std::exchange
+ *   - std::declval
+ *   - std::integer_sequence
+ *   - include <algorithm> to get default std::swap
+ *   - mstd::swap - substitute for std::swap that can move
+ *   - std::swap(array)
+ * - Swap assistance, to ensure moves happen on ARM C 5
+ *   - mstd::swap - alias for std::swap, or a local moving implementation for ARM C 5
+ * - For all toolchains, C++17/20 backports:
+ *   - mstd::as_const
+ */
+
+#include <utility>
+
+namespace mstd {
+using std::swap;
+
+namespace rel_ops { using namespace std::rel_ops; }
+using std::initializer_list;
+using std::exchange;
+using std::forward;
+using std::move;
+// No exceptions in mbed OS
+template <typename T>
+T &&move_if_noexcept(T &t) noexcept
+{
+    return mstd::move(t);
+}
+using std::declval;
+using std::make_pair;
+using std::get;
+using std::pair;
+using std::integer_sequence;
+
+// C++17 [utility.as_const] */
+#if __cpp_lib_as_const >= 201510
+using std::as_const;
+#else
+template <typename _TypeT>
+constexpr std::add_const_t<_TypeT> &as_const(_TypeT &__t) noexcept
+{
+    return __t;
+}
+
+template <typename _TypeT>
+void as_const(_TypeT &&) = delete;
+#endif
+
+} // namespace mstd
+
+#endif // MSTD_UTILITY_