Don't report errors if we can't set serial mode

That's just silly and breaks using the simulator.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

src/serial_posix.c

@@ -418,8 +418,10 @@ serial_configure (serial_t *device, int baudrate, int databits, int parity, int
 
 	// Apply the new settings.
 	if (tcsetattr (device->fd, TCSANOW, &tty) != 0) {
+#if 0 // who cares
 		SYSERROR (device->context, errno);
 		return -1;
+#endif
 	}
 
 	// Configure a custom baudrate if necessary.