Build issue - needs linking to boost unit test

[hjanetzek]

Building SFCGAL with boost 1.48 on Ubuntu 12.04 produces an undefined reference. When I comment out these two lines from vtk.h it works for me:

#include <boost/test/unit_test.hpp>
using namespace boost::unit_test;

output when linking with "-z defs":

CMakeFiles/SFCGAL.dir/algorithm/difference.cpp.o:difference.cpp:function boost::unit_test::singleton<boost::unit_test::unit_test_log_t>::instance(): error: undefined reference to 'vtable for boost::unit_test::unit_test_log_t'
collect2: error: ld returned 1 exit status

[vmora]

Thanks a lot.