make distcheck fails on fedora 29 (automake 1.16)

Failure can be found on Jenkins: https://jenkins.isc.org/job/kea-master-distcheck/194/execution/node/99/log/

Hypothesis is that it fails due to wrong dependency generated by automake or some missing dependencies on Kea side. In src/lib/log/tests/Makefile generated on Fedora 29 there is distdir that depends on BUILT_SOURCES which depend on log_test_messages.{c|hh} which depend on s-messages which uses src/lib/log/compiler/kea-msg-compiler. As can be seen in this chain there is no dependency on this compiler. On other systems distdir does not depend on BUILT_SOURCES and due to this it works there.

My proposed solution is getting rid of this semi-circular dependency for compiling some source to generate some other source for further compilation and replace this compiler with compiler written in some interpreted language (e.g. Python) that does not require compilation.