libstdc++: Replace dg-options "-std=c++11" with dg-add-options strict_std

libstdc++: Replace dg-options "-std=c++11" with dg-add-options strict_std

These tests can (and should) also be run for later standards, so replace
the { dg-options "-std=c++11" } with { dg-add-options strict_std } and a
target selector for c++11.

libstdc++-v3/ChangeLog:

	* testsuite/23_containers/deque/48101-2_neg.cc: Replace
	dg-options with target selector.
	* testsuite/23_containers/forward_list/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/list/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/map/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/map/48101_neg.cc: Likewise.
	* testsuite/23_containers/multimap/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/multimap/48101_neg.cc: Likewise.
	* testsuite/23_containers/multiset/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/set/48101-2_neg.cc: Likewise.
	* testsuite/23_containers/unordered_map/48101-2_neg.cc:
	Likewise.
	* testsuite/23_containers/unordered_multimap/48101-2_neg.cc:
	Likewise.
	* testsuite/23_containers/unordered_multiset/48101-2_neg.cc:
	Likewise.
	* testsuite/23_containers/unordered_set/48101-2_neg.cc:
	Likewise.
	* testsuite/23_containers/vector/48101-2_neg.cc: Likewise.