Regressions on trunk at revision 174810 vs revision 174806

[H.J. Lu ia32 Core 2/i7]

New failures:

New passes:
FAIL: 20_util/is_copy_assignable/value.cc (test for excess errors)
FAIL: 20_util/is_move_assignable/value.cc (test for excess errors)
FAIL: 20_util/is_nothrow_move_assignable/value.cc (test for excess errors)
FAIL: 20_util/unique_ptr/cons/pointer_array_convertible_neg.cc (test for excess errors)
FAIL: 23_containers/map/modifiers/insert/2.cc (test for excess errors)
FAIL: 23_containers/map/modifiers/insert/3.cc (test for excess errors)
FAIL: 23_containers/unordered_map/requirements/explicit_instantiation/1.cc (test for excess errors)
FAIL: 23_containers/unordered_multimap/insert/multimap_single.cc (test for excess errors)
FAIL: 23_containers/unordered_multimap/requirements/explicit_instantiation/1.cc (test for excess errors)