[ Chris Lamb ]
* Mask stderr from the extract-vmlinux script.
* Make it much more explicit that we return 'success' from the
  extract-vmlinux script instead of just falling through to the bottom of the
  script.
* Use Difference.from_operation in an attempt to pipeline the output of
  extract-vmlinux, potentially avoiding it all residing in memory. This is an
  attempt to prevent out of memory issues on try.diffoscope.org.

[ Siva Mahadevan ]
* Use --print-armap long option with nm in the "ar" comparator for wider
  compatibility.