title: CMake complains "The CXX compiler identification is unknown"
body: <p>I am following this <a href="https://superuser.com/questions/58079/download-and-install-newer-kde-without-root-access">thread</a> and this <a href="http://techbase.kde.org/Getting_Started/Build/Example" rel="noreferrer">one</a> to build my own KDE without a sudo permission. Since there was no Git and CMake installed on the workstation. I just had them both installed under <strong>/home/&lt; user></strong> and added <strong>/home/&lt; user>/bin</strong> and <strong>/home/&lt; user>/lib</strong> to both PATH and LD_LIBRARY_PATH. 
  Since KDE build only supports CMake, not configure. So I have to set the prefix via CMake, like this: <code>cmake ~/kde-devel/src/kdelibs -DCMAKE_INSTALL_PREFIX=/home/&lt;user&gt;</code>. At this point I got below error:</p>
  
  <pre><code>&gt; ~/bin/cmake ~/kde-devel/src/kdelibs -DCMAKE_INSTALL_PREFIX=/home/&lt;user&gt;
  -- The CXX compiler identification is unknown
  -- Check for working CXX compiler: /home/gnu/bin/c++
  -- Check for working CXX compiler: /home/gnu/bin/c++ -- broken
  CMake Error at /home/&lt;user&gt;/share/cmake-2.8/Modules/CMakeTestCXXCompiler.cmake:45 (MESSAGE):
    The C++ compiler "/home/gnu/bin/c++" is not able to compile a simple test
    program.
  
    It fails with the following output:
  
     Change Dir: /home/&lt;user&gt;/kde-devel/build/kdelibs/CMakeFiles/CMakeTmp
  
  
  
    Run Build Command:/usr/bin/gmake "cmTryCompileExec/fast"
    ...
  </code></pre>
  
  <p>I checked that there are 2 C++ compilers:</p>
  
  <pre><code>&gt; where c++
  /home/gnu/bin/c++
  /usr/bin/c++
  </code></pre>
  
  <p>Should I set CMake default C++ compiler to <code>/usr/bin/c++</code>? and how? Or is there any way to fix this issue?</p>