Log the actual number of bytes sent on the wire to /var/log/ftpd

instead of the disk size of the file sent.   Since the log file
is intended to provide data for anonymous ftp traffic accounting,
the disk size of the file isn't really informative in this case.

PR:		bin/72687
Submitted by:	Oleg Koreshkov
MFC after:	1 week

libexec/ftpd/ftpd.c

@@ -1701,8 +1701,8 @@ retrieve(char *cmd, char *name)
 	time(&start);
 	send_data(fin, dout, st.st_blksize, st.st_size,
 		  restart_point == 0 && cmd == 0 && S_ISREG(st.st_mode));
-	if (cmd == 0 && guest && stats)
-		logxfer(name, st.st_size, start);
+	if (cmd == 0 && guest && stats && byte_count > 0)
+		logxfer(name, byte_count, start);
 	(void) fclose(dout);
 	data = -1;
 	pdata = -1;