(ipsec) fix syslog output, eventually we should switch to the new style loggers, but for now it's better to make sure charondebug is respected.

From the docs:

Starting with version 4.2.9, strongSwan provides a much more flexible configuration of the loggers. Logger configurations in strongswan.conf have a higher priority than charondebug in ipsec.conf: If you define any loggers in strongswan.conf, charondebug does not have any effect at all.

(cherry picked from commit b9392f59)