test-random-input.sh doesn't run on macOS

[CodingMarkus]

On macOS you just run into tr: Illegal byte sequence

The problem is that the script does not set LC_ALL=C and uses echo -e instead of printf. Also it does not suppress expected parser errors.

[CodingMarkus]

I fixed that problem and will provide a pull request shortly.

And after fixing it, I found an actual bug in the C code as well. See #8