Fix a memory leak with the variable logfname

[gad]

Summary

Fix a memory leak with the variable logfname. logfname was
alloc-ed with strdup but never freed. This problem was found with clang's
static analysis tool scan-build/scan-view

Test Plan

Run scan-build before and after, verify the problem is resolved.
Manual review use of pointer in source.

[gad]

Many years ago I did some work on newsyslog. I could handle the review and commit of this update if that's okay with other reviewers.

[emaste]

In D9637#208228, @gad wrote:

I could handle the review and commit of this update if that's okay with other reviewers.

That's fine with me!

[stevek]

Fine with me as well.

[emaste]

Ping @gad

[gad]

In D9637#283208, @emaste wrote:

Ping @gad

I have a few weeks coming up where I won't be busy at work, so I should get to this.

[gad]

So, I'm finally getting around to looking at this. The delay was that I didn't have a freebsd-12.current system running. And now that I have a current system to test changes on, it looks like this issue was solved back in revision 303449 by ed, Thu Jul 28 16:02:30 2016 UTC. See revision 303449

So this could be closed as "already fixed", except that I don't see how I could do that!

Sorry for the long delay.

[gad]

Let's see if I can finally figure out how to close this review-request (after almost 3 years...)

[gad]

The problem is fixed by this revision was already fixed back in Jul 28 16:02:30 2016.