It's better if the tests aren't interactive, since they're intended for
running on CI as well as to give an idea of whether building was
successful, rather than to give an idea of what has gone wrong.
Need to pass the LD_LIBRARY_PATH all the way through or racket doesn't
know where to look. I really don't know why it doesn't work to just set
it at the top level in the script, but it didn't (on my Mac, at least).
