[boost] numeric/conversion/detail/meta: void_ in boost::mpl namespace

Hi, Is BOOST_MPL_AUX_VOID_SPEC_PARAM supposed to be used by other libraries than MPL? The conversion library uses it (it is the only one to use it) and it obviously results in an error since void_ is in the boost::mpl namespace. This error is flagged by GCC, CodeWarrior, Como, and Intel (Linux). I won't suggest a patch since I'm not even sure to understand what this macro is supposed to do (is there any documentation or is it an undocumented internal macro?), but it can't be a bad thing to remove any reference to BOOST_MPL_AUX macros from the conversion library. Regards, Guillaume