don't emit duplicate function names in --no-hunks mode

When including hunks in the generated file, it makes sense to make a
new entry for each hunk, because this mode implies a lot of hand
editing.  However, with --no-hunks, it seems friendlier to also omit
duplicate function names.  This patch eliminates these duplicates.
Merge pull request #2 from tromey/master

don't emit duplicate function names in --no-hunks mode