[Crash-utility] Faster iteration on list of struct.field

Hi, I often find myself dumping a bunch of addresses to files to iterate with 'struct_name.field < file_with_addresses', but that is horribly slow for large number of iterations. `help list` comment for -S vs. -s made me try to use `rd` instead, e.g. get offset manually from `struct -o` then use rd instead like `rd -o xx < addr_list | awk '{ print $2 }' > value_list` -- and that is infinitely better. Would it make sense to add a similar option to 'struct' instead so one could do e.g. `struct -S struct_name.field addr` instead of the dance I was doing? (That would require to cache field offset in crash and not query it again everytime, from a quick look at the code, but we could only cache one and still gain a lot for such iterations...) Am I missing another more practical way of doing this? (I guess it's not so bad now I came up with using 'rd', but that was non-obvious to me. My use case here involved following a couple of pointers from a list so I dumped the first pointer to follow from list with -S struct1.field1, but then the following iteration just wouldn't end naively) Thanks, -- Dominique