s3: Allow full_audit to play nice with smbd if it's using syslog

s3: Allow full_audit to play nice with smbd if it's using syslog

Explictly pass the facility from both smbd and full_audit to syslog.
Really the only major change is to not call openlog() in full_audit if
WITH_SYSLOG is defined, which implies that smbd is already using
syslog.  This allows full audit to piggy-back on the same ident as
smbd, while still differentiating the logging via the facility.