Use std::addressof in insert iterators, allocators and promises

Use std::addressof in insert iterators, allocators and promises

	PR libstdc++/69105
	PR libstdc++/69106
	PR libstdc++/69114
	* include/bits/stl_iterator.h (back_insert_iterator,
	front_insert_iterator, insert_iterator): Use __addressof (LWG 2324).
	* include/bits/uses_allocator.h (__use_alloc): Use __addressof.
	* include/std/future (__future::base::_State_baseV2::__setter):
	Likewise.
	* include/std/scoped_allocator (__outermost): Likewise.
	* testsuite/20_util/scoped_allocator/69114.cc: New.
	* testsuite/20_util/uses_allocator/69114.cc: New.
	* testsuite/30_threads/promise/69106.cc: New.

From-SVN: r232129