title: use environment variables in eclipse
body: <p>I have a a eclipse CDT project using a Cross GCC toolchain. The path of the cross compiler has to be set in the toolchain settings: C/C++ Build -> Settings -> Cross Settings -> Path.</p>
  
  <p>Because of sharing this project with other people, the path to the cross compiler should be in an environment variable which I called LINUX_DEVKIT_PATH.  </p>
  
  <p>I defined LINUX_DEVKIT_PATH as an environment variable and used "${LINUX_DEVKIT_PATH}/bin" in the C/C++ Build -> Settings -> Cross Settings -> Path field. But with this settings the compiler couldn't be found.
  I also tried to used C/C++ Build -> Environment -> Select... to add the variable to the list. The environment variable is found and appears in the list with the origin User: Config. </p>