Fix Travis error on Mac

.travis.yml

@@ -109,6 +109,7 @@ before_install:
   - wget http://anaconda.org/omnia/ccache/3.2.4/download/${TRAVIS_OS_NAME}-64/ccache-3.2.4-0.tar.bz2
   - mkdir -p $HOME/ccache && tar xf ccache-3.2.4-0.tar.bz2 -C $HOME/ccache
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
+      brew cask uninstall oclint;
       brew install fftw;
       brew install -y https://raw.githubusercontent.com/Homebrew/homebrew-core/5b680fb58fedfb00cd07a7f69f5a621bb9240f3b/Formula/doxygen.rb;
       sudo easy_install pytest;