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

usr.sbin/newsyslog/newsyslog.c

@@ -793,6 +793,9 @@ usage(void)
 	fprintf(stderr,
 	    "usage: newsyslog [-CFNPnrsv] [-a directory] [-d directory] [-f config_file]\n"
 	    "                 [-S pidfile] [-t timefmt] [[-R tagname] file ...]\n");
+	/* Free global dynamically-allocated storage. */
+	free(timefnamefmt);
+	free(requestor);
 	exit(1);
 }