FIX: Stream-IO-test.reds for Linux

[isoux]

When compiled for Linux and run on it, the test does not produce a test-oi.bin file but a file named "t". It is obvious that the way of using directive #16 (variable name: #u16 "test-io.bin") is not suitable for Linux. After removing directive #u16 the mentioned file is produced with the full name. I couldn't have found a better solution with my novice experience.