Merge pull request #27 from bitnot/master

Fix Travis CI build step for MacOS

Author: aetilius

.travis.yml

@@ -15,7 +15,7 @@ matrix:
 
 before_install:
   - if [ $TRAVIS_OS_NAME == "linux" ]; then sudo apt-get install -y libpng-dev libjpeg-dev libtiff-dev libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libsndfile1-dev libsamplerate0-dev libmpg123-dev; fi
-  - if [ $TRAVIS_OS_NAME == "osx" ]; then travis_retry brew upgrade && travis_retry brew install libpng libtiff libjpeg ffmpeg mpg123; fi
+  - if [ $TRAVIS_OS_NAME == "osx" ]; then travis_retry brew install libpng libtiff libjpeg ffmpeg mpg123; fi
 before_script:
   - mkdir -p build
   - cd build