Install fail CMAKE_CXX_COMPILER not set, after EnableLanguage

[Whytehorse]

$ sudo ./install.sh
Prefix set to /home/ben/torch-cl/install
Installing Lua version: LUAJIT21
CMake Error at /usr/share/cmake-3.5/Modules/CMakeDetermineCXXCompiler.cmake:56 (message):
  Could not find compiler set in environment variable CXX:

  g++-4.9.

Call Stack (most recent call first):
  CMakeLists.txt


CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage