fix gxx isntall

Author: pythoneer

.travis.yml

@@ -3,8 +3,8 @@ before_install:
     - sudo add-apt-repository --yes ppa:ubuntu-toolchain-r/test
     - sudo apt-get update -qq
     - sudo apt-get install -qq qt5-qmake qtbase5-dev qtdeclarative5-dev libqt5webkit5-dev libsqlite3-dev libx11-dev libxtst-dev
-    - sudo apt-get install -qq g++-4.8
-    - export CXX="g++-4.8" CC="gcc-4.8"
+    - sudo apt-get install gcc-4.8
+    - sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50
 script:
     - g++ --version
     - gcc --version