deeper param analysis for unknown ioctls

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on July 27, 2011 18:08:40_

the current unknown syscall analysis one-level pointer consideration can be extended in a targeted way to look for secondary pointers within the input and output buffers of NtDeviceIoControlFile, which may well be worthwhile given that we don't really expect to understand the data structures of all the ioctls we've seen anytime soon.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=514_