Fix two memory leaks in syslogd

A memory leak in syslogd for processing of forward actions was
reported. This modification adapts the patch submitted with that bug
to fix the leak. While testing the modification, another leak was also
found and fixed.

PR: 198385
Submitted by: Sreeram <sreeramabs@yahoo.com>
Reported by: Sreeram <sreeramabs@yahoo.com>
Reviewed by: hrs
MFC after: 1 week
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D14510