conflicts_with is a thin wrapper around Requirement which simplifies
marking conflicts between formulae.
ClosesHomebrew/homebrew#13687.
Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
* par2tbb conflicts with par2, so issue a warning if par2 is installed.
* update handling of clang failure; this should be changed once
fails_with_clang is available