Try adding -lboost_thread and -lboost_system to your build path.
Did a fresh install of Xubuntu 16.04 but again the build failed.
It had to do with the cmath and math.h libraries it was an easy fix and is now also on Github.
So both the QT client and headless daemon can be build on 16.04.
Just follow the install instructions on the Digitalcoin Forum :-)
https://forum.digitalcoin.tech/viewtopic.php?pid=71#p71