[writeboost] fix: discard the subsequent logs if checksums don't match

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
[writeboost] refactor: Move advancing last_writeback_segment_id into
do_writeback_segs

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
Merge pull request #23 from akiradeveloper/feature/fix-log-replay

Feature/fix log replay