Don't sort debug output.

I was being silly - that's what sort(1) is for.  And, it turns out, sort
is slightly faster, anyways:

    [$]> time sh -c './extract.rb debug > /dev/null'
    5.50s user 0.00s system 98% cpu 5.563 total

(after these changes):

    [$]> time sh -c './extract.rb debug | sort -nr > /dev/null'
    5.27s user 0.03s system 99% cpu 5.328 total