Fix experimental::pmr typedefs and add tests

Fix experimental::pmr typedefs and add tests

The typedefs in <experimental/regex> and <experimental/string> don't
need to be in the __cxx11 namespace, because they are only aliases and
so will have the same mangled name as the underlying types.

	* include/experimental/regex: Remove begin/end macros for namespace.
	* include/experimental/string: Likewise.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_deque.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_forward_list.cc: New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_list.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_map.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_match.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_multimap.cc: New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_multiset.cc: New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_set.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_string.cc:
	New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_unordered_map.cc: New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_unordered_multimap.cc: New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_unordered_multiset.cc: New test.
	* testsuite/experimental/polymorphic_allocator/
	pmr_typedefs_unordered_set.cc: New test.
	* testsuite/experimental/polymorphic_allocator/pmr_typedefs_vector.cc:
	New test.

From-SVN: r263568