Always close commitlog files
Always close commitlog files

We were using segment::_closed to decide whether _file was already
closed. Unfortunately they are not exactly the same thing. As far as
I understand it, segments can be closed and reused without actually
closing the file.

Found with a seastar patch that asserts on destroying an open
append_challenged_posix_file_impl.

Fixes #4745.

Signed-off-by: Rafael Ávila de Espíndola <1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>
Message-Id: <20190721171332.7995-1-1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>

avikivity/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla