title: WebAssembly emsdk installation fails
body: <p>I want to install <a href="https://github.com/emscripten-core/emsdk" rel="nofollow noreferrer">EMSDK</a> for WASM compilation but EMSDK installation fails.</p>
  
  <p>I've already installed Cmake (3.14.0-rc1 also tried 3.5.2 then) on Ubuntu 16.</p>
  
  <p>When I run <code>./emsdk install sdk-incoming-64bit binaryen-master-64bit</code> it fails:</p>
  
  <pre><code>CMake Error: CMake was unable to find a build program corresponding to "Unix Makefiles".  CMAKE_MAKE_PROGRAM is not set.  You probably need to select a different build tool.
  CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage
  CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage
  CMake Error: CMAKE_ASM_COMPILER not set, after EnableLanguage
  -- Configuring incomplete, errors occurred!
  See also "/home/emsdk/clang/fastcomp/build_incoming_64/CMakeFiles/CMakeOutput.log".
  CMake invocation failed due to exception!
  Working directory: /home/emsdk/clang/fastcomp/build_incoming_64
  Command '['cmake', '-G', 'Unix Makefiles', '-DCMAKE_BUILD_TYPE=Release', '-DPYTHON_EXECUTABLE=/usr/bin/python', '-DLLVM_TARGETS_TO_BUILD=X86;JSBackend', '-DLLVM_INCLUDE_EXAMPLES=OFF', '-DCLANG_INCLUDE_EXAMPLES=OFF', '-DLLVM_INCLUDE_TESTS=OFF', '-DCLANG_INCLUDE_TESTS=OFF', '-DLLVM_ENABLE_ASSERTIONS=OFF', '/home/emsdk/clang/fastcomp/src']' returned non-zero exit status 1
  Installation failed!
  </code></pre>