[ros-diffs] [ion] 24422: - Add internal EX_CALLBACK Object to NDK. (Callback blocks are a new NT 5.2 kernel mechanism much like RunOncs blocks in Vista user-mode). They're managed by rundown protection and fast-referencing through interlocked calls to push/pop/sychrnonize system callbacks. - Add ObOpenObjectByName to NDK, since this API is not documented in official headers.