Kea does not compile with boost installed into the system by default on FreeBSD 11.2

./configure fails this way (form config.log):

configure:20063: c++ -o conftest -g -O2  -DOS_BSD -I/usr/local/include  conftest.cpp  -lboost_system  >&5
/usr/bin/ld: cannot find -lboost_system
c++: error: linker command failed with exit code 1 (use -v to see invocation)

There is a workaround:

./configure --with-boost-include=/usr/local/include --with-boost-lib-dir=/usr/local/lib