genomics: fix compilation warnings

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
genomics: add a function to flush arcs

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
genomics: arc classifier should be stateful

Link: https://github.com/GeneAssembly/biosal/issues/742
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>