CmdEscapeCheck(): signals buffer overflow

If the RxBuffer[] buffer is too small to contain the reader response
then IFD_ERROR_INSUFFICIENT_BUFFER is returned.

Before the patch the returned buffer was silently truncated and
IFD_SUCCESS was returned.

Thanks to Maximilian Stein for the bug report
"[Pcsclite-muscle] libccid IFDHControl() / CmdEscape() might truncate reader response"
http://lists.alioth.debian.org/pipermail/pcsclite-muscle/Week-of-Mon-20170213/000816.html

src/commands.c

@@ -1008,7 +1008,10 @@ RESPONSECODE CmdEscapeCheck(unsigned int reader_index,
 	/* copy the response */
 	length_out = dw2i(cmd_out, 1);
 	if (length_out > *RxLength)
+	{
 		length_out = *RxLength;
+		return_value = IFD_ERROR_INSUFFICIENT_BUFFER;
+	}
 	*RxLength = length_out;
 	memcpy(RxBuffer, &cmd_out[10], length_out);