compile cgal-python

I tried to build cgal-python and had the following errors (just a snippet):

In file included from /opt/local/include/boost/config.hpp:40,
             from /opt/local/include/CGAL/config.h:37,
             from /opt/local/include/CGAL/basic.h:28,
             from Kernel_module.cpp:21,
             from All_files_at_once.cpp:1:
/opt/local/inc开发者_Python百科lude/boost/config/select_stdlib_config.hpp:17:19: error: cstddef: No such     file or directory

Where are the header files of standard C library on MacOS Lion?

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I upgraded XCode to 4.1 and now the above errors are gone.