Check also that locking succeeds after the writer closes the WARC file.
Remove parametrize from ``test_warc_writer_locking``, test only for the
``no_warc_open_suffix=True`` option.
Change `1` to `OBTAINED LOCK` and `0` to `FAILED TO OBTAIN LOCK` in
``lock_file`` method.
On Linux, `fcntl.flock` is implemented with `flock(2)`, and
`fcntl.lockf` is implemented with `fcntl(2)` — they are not compatible.
Java `lock()` appears to be `fcntl(2)`. So, other Java programs working
with these files work correctly only with `fcntl.lockf`.
`warcprox` MUST use `fcntl.lockf`
