In `-std=c++11`, most POSIX functions/definitions cannot be used. Also `putenv ()` and `chroot ()` cannot be used. These missing raises error in compiling LilyPond.
We can define `M_PI` if there is no `M_PI` definition. We can implement `strdup ()` alternative by using only strict C++11 standard functions. If I understand correctly, implementing `getenv ()` or `chroot ()` is very difficult. https://codereview.appspot.com/579270051/
