Merge branch 'sp/shortlog-missing-lf'

Merge branch 'sp/shortlog-missing-lf'

When a line to be wrapped has a solid run of non space characters
whose length exactly is the wrap width, "git shortlog -w" failed to
add a newline after such a line.

* sp/shortlog-missing-lf:
  strbuf_add_wrapped*(): Remove unused return value
  shortlog: fix wrapping lines of wraplen