simplify syslog, add vsyslog interface (nonstandard)

simplify syslog, add vsyslog interface (nonstandard)

with datagram sockets, depending on fprintf not to flush the output
early was very fragile; the new version simply uses a small fixed-size
buffer. it could be updated to dynamic-allocate large buffers if
needed, but i can't envision any admin being happy about finding
64kb-long lines in their syslog...