Returns a dynamically-typed CSharedAllocator built around a given statically- typed allocator a of type A. Passing a pointer to the allocator creates a dynamic allocator around the allocator pointed to by the pointer, without attempting to copy or move it. Passing the allocator by value or reference behaves as follows.

• If A has no state, the resulting object is allocated in static shared storage.
• If A has state and is copyable, the result will std.algorithm.mutation.move the supplied allocator A a within. The result itself is allocated in its own statically-typed allocator.
• If A has state and is not copyable, the result will move the passed-in argument into the result. The result itself is allocated in its own statically-typed allocator.