Comment 5 for bug 1293295

AFAIU enforcing c++11 with current trunk is only necessary if compiling with libc++ (instead of libstdc++), i.e. on Mavericks.

It certainly is not needed on Lion, and will fail on that platform with more advanced C++11 features anyway (e.g. the compile time checking mentioned in this thread: <http://thread.gmane.org/gmane.comp.graphics.inkscape.devel/42740>).