[Bug libstdc++/66262] [REGRESSION] testsuite failure with libstdc++ (gcc-5) and g++-4.9 together

["trippels at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66262

--- Comment #7 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Thanks.

I get with gcc-4.9:
...
Linking CXX executable ../../../Binaries/test_runner
CMakeFiles/test_runner.dir/test_runner.cpp.o:test_runner.cpp:function
boost::filesystem::path::path<boost::filesystem::directory_entry>(boost::filesystem::directory_entry
const&,
boost::enable_if<boost::filesystem::path_traits::is_pathable<boost::decay<boost::filesystem::directory_entry>::type>,
void>::type*): error: undefined reference to
'boost::filesystem::path_traits::dispatch(boost::filesystem::directory_entry
const&, std::string&)'
collect2: error: ld returned 1 exit status
tests/common/TestRunner/CMakeFiles/test_runner.dir/build.make:113: recipe for
target 'Binaries/test_runner' failed

Note that I'm using the new C++ ABI already and I don't have a testbox
that uses the old ABI.

So someone that still uses the old ABI needs to debug this further...