Comment 2 for bug 388608

OK, better version that switches to syslog user earlier to avoid issue with the kmsg pipe not giving us any data if we read from it before switching uid/gid.

So things this patch does:
1) Backports the 'DropPriv' config values from upstream
2) Copies the dd-shovels-proc-kmsg-to-readable-location logic from sysklogd and adds a config value to change klog location
3) Handles upgrade from sysklogd by doing the following:
   A) Splits rsyslog.conf into two parts: config stuff and rules
   B) If we're upgrading to this version or later and /etc/syslog.conf exists *and* is modified by user, then copy it to /etc/rsyslog.d/default.conf
   C) Merge our default rules into /etc/rsyslog.d/default.conf using ucf