Fix assertions for move assignment of trivial types

Fix assertions for move assignment of trivial types

	PR libstdc++/69478
	* include/bits/stl_algobase.h (__copy_move<_IsMove, true,
	random_access_iterator_tag>): Check is_move_assignable when moving.
	(__copy_move_backwards<_IsMove, true, random_access_iterator_tag>):
	Likewise.
	* testsuite/25_algorithms/copy/move_iterators/69478.cc: New.
	* testsuite/25_algorithms/copy_backward/move_iterators/69478.cc: New.
	* testsuite/25_algorithms/move/69478.cc: New.
	* testsuite/25_algorithms/move_backward/69478.cc: new.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@232842 138bc75d-0d04-0410-961f-82ee72b054a4