Adds iterator singular check within the valid range check.

	* include/debug/functions.h: Remove <bits/move.h> include.
	(__check_singular_aux, __check_singular): Move...
	* include/debug/helper_functions.h:
	(__check_singular_aux, __check_singular): ...here.
	(__valid_range_aux): Adapt to use latter.
	Add <bits/move.h> include.
	* testsuite/25_algorithms/copy/debug/2_neg.cc: New.

From-SVN: r278658