[boost] [test] New location of fraction_tolerance()

There used to be a function named fraction_tolerance() in boost::test_tools (in <boost/test/floating_point_comparison.hpp>) that marked that a floating-point comparison uses a fraction as its tolerance value. That function seems to have disappeared in one of the recent checkins. What is the intended replacement? There is no boost::math::fpc::fraction_tolerance which is what appears from the new naming pattern to be the correct name. Is there an equivalent to that function? -- Jeremiah Willcock