Fix the TFTP client when performing a RRQ for files smaller than 512 bytes

and the server not sending an OACK:
* Close the file.
* Report the correct the number of received blocks.

MFC after:		1 week

libexec/tftpd/tftp-transfer.c

@@ -280,6 +280,8 @@ tftp_receive(int peer, uint16_t *block, struct tftp_stats *ts,
 		}
 
 		if (fb_size != segsize) {
+			ts->blocks++;
+			write_close();
 			gettimeofday(&(ts->tstop), NULL);
 			return;
 		}