[boost] [test] max_digits10 code breaks regression testing for many older platforms

Paul, I noticed that the change to set_precision in Boost.Test (rev 78908) seems to have broken regression testing on the trunk for all of the platforms that don't have max_digits10 in their standard library (even for non-math-related tests). Is there any way to restrict this new code to only platforms that can support it? Thanks, -Dave