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.
From-SVN: r232842