syslogd: undo regression after r326573

Restore ability for our syslogd to collect pre-RFC3164 formatted
messages from remote hosts that was broken with r326573.

For example, the line from Cisco SCE8000 splitted for readability:

1130: 03:37:57: %USER-6-PORT_OPERSTATUS_CHANGE_TRAP: CPU#000 trap:link
down EntityAdminState: 4 EntityAlarmStatus: 32

Such line was collected and stored before mentioned change
but silently dropped after that. Now syslogd saves it again.

Note that parsing of RFC5424 format not changed.

MFC after: 1 month