syslogd: make "-O -" log to stdout

function                                             old     new   delta
packed_usage                                       29871   29908     +37
log_locally                                          404     440     +36
syslogd_main                                        1966    1956     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 73/-10)             Total: 63 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
syslogd: syslogd: don't *decrement* log_file->size on write failures

Even if we fail to write to a log-file, and it's not growing,
it's not *shrinking* either....

Signed-off-by: Joshua Judson Rosen <jrosen@harvestai.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>