Add __attribute__((malloc) to allocator and remove unused code

Add __attribute__((malloc) to allocator and remove unused code

	* include/bits/valarray_array.h (__valarray_get_memory): Remove.
	(__valarray_get_storage): Call operator new directly. Remove ignored
	top-level restrict qualifier and add malloc attribute instead.
	(_Array<_Tp>::_Array(size_t)): Remove unused constructor.

From-SVN: r260230