program_options fails with clang++/libc++

[Jörg Plate <patterner@…>]

trying to use it fails with

undefined reference to `boost::program_options::options_description::options_description
(std::__1::basic_string<char, std::__1::char_traits<char>,
 std::__1::allocator<char> > const&, unsigned int, unsigned int)'

libboost_program_options.so.1.62.0 has

000000000003ac70 T boost::program_options::options_description::options_description
(std::__cxx11::basic_string<char, std::char_traits<char>,
 std::allocator<char> > const&, unsigned int, unsigned int)

boost was built with "-stdlib=libc++" and clang 3.9