logger: make local sockets to try both stream and datagram

When journald, from systemd, is in use logger gave following error.

$ logger --socket /dev/log test logger: connect /dev/log: Protocol wrong
type for socket

The journald supports only AF_DGRAM, and nothing else.  Support for
AF_STREAM sockets was dropped because it messed up message ordering.

From an users point of view necessity to add --udp (UNIX(TM) Datagram
Protocol?) option when talking to syslog via unix socket felt confusing
and wrong.  The command should know what is the socket type, and silently
use the correct one, unless the type is explicitely defined.

CC: Karel Zak <kzak@redhat.com>
Adviced-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>