Something is wrong with the entry (probably a missing timestamp), so no point
in rotating. But suppress the error in process_source(), so that the processing
of the data stream continues.
Also, just return 0 from writer_write() on success, the only caller doesn't
care.
msan doesn't understand sscanf with %ms, so it falsely reports unitialized
memory. Using sscanf with %ms is quite convenient in
socket_address_parse_netlink(), so let's just not run the fuzzer for
ListenNetlink= at all for now. If msan is fixed, we can remove this.
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=6884
Zbigniew Jędrzejewski-Szmek