[C++-sig] compile libboost_python.a with '-fPIC' flag on x86_64

[Grant Tang]

Hi,

I need to compile a static boost.python library with '-fPIC' CFLAGS. I don't
know how to do it with bjam/jamfile. 

Since my platform is x86_64 based, the libboost_python.a compiled without
'-fPIC' will not make my project compiled. 

Thanks,
Grant