Note however that scc_info does not provide a precise accept/reject
characterization for SCCs when using Fin acceptance.  However whenever
it tells that an SCC is rejecting, scc_filter_states() may safely remove
it.

* src/twaalgos/sccfilter.cc (scc_filter_states): Allow on any TωA.
(scc_filter): Only use acceptance simplifications on TGBA.
* src/tests/unambig.test: Add a co-Büchi test.