[boost] [compute] Remove boost::chrono lib dependencie

Hi, Would it be possible to remove the dependency for boost/chrono is boost/compute/detail/duration.hpp. As it already supports std::chrono via a macro, couldn't the inclusion of boost/chrono.hpp be excluded? As it is now, boost compute is dependent on having libboost_chrono-vc140-mt-gd-1_62.lib built. /Viktor