[Crash-utility] do_radix_tree() function in filesys.c

I notice that there is a function to look at radix trees in filesys.c, but it's not called by anything in the crash executable from what I can see. In fact when I wrote a small extension to call it, I see that it simply doesn't work for several reasons (wrong structures, incorrect dereferencing of pointers). Attached is a patch which addresses these. I've tested it on i686, x86_64 and ia64. If you think that this type of ("utility") code is best left out of crash, then let's just remove this from the source and not clutter it with dead code. Personally, I think it's nice to have it there... when it works. Regards, Alan Tyson, HP.