Use shared lib for the boost test framework
Turns out the unconspicuously looking
#include <boost/test/included/unit_test.hpp>
includes the entire boost test framework in every single unit test compilation unit.
Simply linking against the boost test framework as a shared lib and switching to
#define BOOST_TEST_DYN_LINK
#include <boost/test/unit_test.hpp>
reduces build time on atpc002
by large fraction, and memory consumption goes down drastically: