BUG/MINOR: tcpcheck: Fix a leak on deinit by releasing ruleset's conf.file

Now healthcheck sections are supported, a ruleset can reference a
configuration file that must be freed on deinit. So let's do so.

No backport needed.

src/tcpcheck.c

@@ -335,6 +335,7 @@ void free_tcpcheck_ruleset(struct tcpcheck_ruleset *rs)
 		LIST_DELETE(&r->list);
 		free_tcpcheck(r, 0);
 	}
+	free((char*)rs->conf.file);
 	free(rs);
 }