Upgrade compiler in Travis

.travis.yml

@@ -5,9 +5,9 @@ before_install:
 # which needs the following ugly dependency incantations to build RocksDB:
  - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
  - sudo apt-get update -qq
- - sudo apt-get install -y -qq gcc-4.8 g++-4.8 zlib1g-dev libbz2-dev libsnappy-dev libjemalloc-dev
- - sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50
- - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 50
+ - sudo apt-get install -y -qq gcc-4.9 g++-4.9 zlib1g-dev libbz2-dev libsnappy-dev libjemalloc-dev
+ - sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 50
+ - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.9 50
  - wget https://gflags.googlecode.com/files/libgflags0_2.0-1_amd64.deb
  - sudo dpkg -i libgflags0_2.0-1_amd64.deb
  - wget https://gflags.googlecode.com/files/libgflags-dev_2.0-1_amd64.deb