formatter.h (__check_singular): Add const on iterator reference.

formatter.h (__check_singular): Add const on iterator reference.

2013-10-25  François Dumont  <fdumont@gcc.gnu.org>

	* include/debug/formatter.h (__check_singular): Add const on
	iterator reference.
	* include/debug/functions.h (__check_singular): Likewise.
	(__check_singular(const _Safe_iterator<_Ite, _Seq>&)): Delete.
	(__check_dereferenceable(const _Ite&)): Add const on iterator
	reference.
	(__check_dereferenceable(const _Safe_local_iterator<>&)): New.
	* include/debug/safe_iterator.h (__check_singular_aux): Review
	comment.
	* testsuite/23_containers/vector/debug/debug_functions.cc: New.
	* testsuite/23_containers/unordered_set/debug/debug_functions.cc:
	New.

From-SVN: r204075