MDEV-22438 add a function similar to std::make_scope_exit()

The idea was borrowed from http://wg21.link/p0052

scope_exit class is a helper, its name is hidden from user in
the namespace detail.

Alternative implementation of scope_exit with std::function
looks slower on goldbolt.org as it may require allocation, etc.
scope_exit doesn't need to own a callable, so beeing a pointer
is enough. And std::decay produces such a pointer from callable.

include/scope.h

@@ -0,0 +1,66 @@
+/*
+   Copyright (c) 2020, MariaDB
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; version 2 of
+   the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA
+*/
+
+#pragma once
+
+#include <type_traits>
+#include <utility>
+
+namespace detail
+{
+
+template <typename Callable> class scope_exit
+{
+public:
+  template <typename F>
+  explicit scope_exit(F &&f) : function_(std::forward<F>(f))
+  {
+  }
+
+  scope_exit(scope_exit &&rhs)
+      : function_(std::move(rhs.function_)), engaged_(rhs.engaged_)
+  {
+    rhs.release();
+  }
+
+  scope_exit(const scope_exit &)= delete;
+  scope_exit &operator=(scope_exit &&)= delete;
+  scope_exit &operator=(const scope_exit &)= delete;
+
+  void release() { engaged_= false; }
+
+  ~scope_exit()
+  {
+    if (engaged_)
+      function_();
+  }
+
+private:
+  Callable function_;
+  bool engaged_= true;
+};
+
+} // end namespace detail
+
+template <typename Callable>
+detail::scope_exit<typename std::decay<Callable>::type>
+make_scope_exit(Callable &&f)
+{
+  return detail::scope_exit<typename std::decay<Callable>::type>(
+      std::forward<Callable>(f));
+}