.osx: Fix typo

Ref. #183.
Merge commit '6383a3fdf0df521d0fda5b11b92849870c30b9e2'

# By Matt Widmann
# Via Mathias Bynens
* commit '6383a3fdf0df521d0fda5b11b92849870c30b9e2':
  .osx: Fix typo