demangle.h: Fix allocator type correctness, i.e.

demangle.h: Fix allocator type correctness, i.e.

	* include/bits/demangle.h: Fix allocator type correctness,
	i.e. make sure that when we instantiate a container with a value
	type and an allocator, the allocator's value type matches the
	container's.
	* include/bits/stl_deque.h (_Deque_alloc_base): Eliminate.
	(_Deque_base): inherit directly from the deque's allocator.  Use
	rebinding instead of _Alloc_traits.  Pick up data members from
	_Deque_alloc_base.
	* include/bits/stl_list.h (_List_alloc_base): Eliminate.
	(_List_base): Inherit directly from the list's allocator.  Use
	rebinding instead of _Alloc_traits.  Pick up data members from
	_List_alloc_base.
	* include/bits/stl_vector.h (_Vector_alloc_base): Eliminate
	(_Vector_base): Inherit directly from the vector's allocator.  Use
	rebinding instead of _Alloc_traits.  Pick up data members from
	_Vector_alloc_base.
	* include/ext/hashtable.h: Fix allocator type correctness (the
	vector of buckets must be passed an allocator for objects of
	type _Node*).  Use rebinding instead of _Alloc_traits.

From-SVN: r74787