Merge pull request #1536 from bluca/ci-osx-missing-dependency

CI run on OSX needs binutils

.travis.yml

@@ -12,6 +12,9 @@ env:
 
 sudo: false
 
+before_install:
+- if [ $TRAVIS_OS_NAME == "osx" ] ; then brew update; brew install binutils ; fi
+
 before_script:
 # ZMQ stress tests need more open socket (files) than the usual default
 # On OSX, it seems the way to set the max files limit is constantly changing, so