This adds a move-only testsuite iterator wrapper to <testsuite_iterators.h>
which will be used in the tests for LWG 3355.  The tests for LWG 3389 and 3390
are adjusted to use this new iterator wrapper.

libstdc++-v3/ChangeLog:

	* testsuite/util/testsuite_iterators.h (input_iterator_wrapper_nocopy):
	New testsuite iterator.
	* testsuite/24_iterators/counted_iterator/lwg3389.cc: Use it.
	* testsuite/24_iterators/move_iterator/lwg3390.cc: Likewise.