Dump file locks' necessary entries to the image, we only support flock and
posix file lock right now.

Changelog since the initial version:
We got file lock info from global list, so the dump_task_file_locks
can be much simpler.
Originally-signed-off-by: Zheng Gu <cengku.gu@huawei.com>
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>