Remove --universal options from homebrew rules.

 - they are ignored at the moment and therefore have not been used in a long time
 - on recent OS X these options are certainly wrong, so this is a prerequisite for merging
   https://github.com/ros-infrastructure/rosdep/pull/304
Merge pull request #4860 from NikolausDemmel/remove-homebrew-universal

Remove --universal options from homebrew rules.