CI run on OSX needs binutils

OSX does not ship with binutils, need to install it before the script
run via brew in order to be able to use greadelf, needed by the
qt-android CI script.

.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