[boost] [config] Deprecate/remove BOOST_NO_INITIALIZER_LISTS

Hi, Once BOOST_NO_0X_HDR_INITIALIZER_LIST has been added to release, I think we should remove BOOST_NO_INITIALIZER_LISTS. It's confusing having both macros. BOOST_NO_INITIALIZER_LISTS is probably useless as it only indicates compiler support and initializer lists can't really be used without the header. I seem to be the only person who uses it, so it might be okay to just remove it immediately or if not, deprecate it and remove it in the next release. Does that sound okay? Daniel