Complete fix for CID 1007454, CID 1007453: Resource leak in newsyslog

The result of a strdup() was stored in a global variable and not freed
before program exit. This is a follow-up to r343906. That change
attempted to plug these resource leaks but managed to miss a code path
on which the leak still occurs. Plug the leak on that path, too.

MFC after: 3 days
Sponsored by: Dell EMC Isilon