Extract upstream KWSys using the following shell commands.

$ git archive --prefix=upstream-kwsys/ ed82989c | tar x
$ git shortlog --no-merges --abbrev=8 --format='%h %s' d79801bb..ed82989c
Brad King (3):
      9baab632 SystemTools: Keep stat st_mtim field existence private
      39475e20 SystemTools: Refactor utimes invocation
      ed82989c SystemTools: Implement nanosecond file times on OS X