rx: strip padding from last block. closes bug 501.

function                                             old     new   delta
rx_main                                              876     974     +98

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/rx.tests

@@ -0,0 +1,27 @@
+#!/bin/sh
+# Copyright 2009 by Denys Vlasenko
+# Licensed under GPL v2, see file LICENSE for details.
+
+. testing.sh
+
+# testing "test name" "options" "expected result" "file input" "stdin"
+
+# Simple one-block file transfer
+# rx => 'C'
+# rx <= SOH <blockno> <255-blockno> <128 byte padded with x1A> <crc> <crc>
+# rx => ACK
+# rx <= EOT
+# rx => ACK
+testing "rx" \
+	"rx rx.OUTFILE | hexdump -vC && cat rx.OUTFILE" \
+"\
+00000000  43 06 06                                          |C..|\n\
+00000003\n\
+???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????" \
+	"" "\1\1\376\
+???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????\
+\x1A\x1A\x1A\x1A\x1A\x4B\xB0\4"
+
+rm -f rx.OUTFILE 2>/dev/null
+
+exit $FAILCOUNT