From looking at the build code, you should be able to just set CC=gcc-4.9 and CXX=g++-4.9 in your environment. This is a pretty standard practice and the reaso

From looking at the build code, you should be able to just set CC=gcc-4.9 and CXX=g++-4.9 in your environment. This is a pretty standard practice and the reason that it's set to "gcc-4.8" rather than "gcc" by default is because it requires real C++11 support in order to compile.