backport 56e28a3fbb7f911e27feac9499f3204d739eead0
2nd attempt at 790af4e400bb8c69ced0c42dff1e8c95b32a0f9e
Workaround Clang CPP issues

This removes the whitespace between `ASSERT` and `(` which Clang chokes upon

This should address #1

(See also ghc/ghc@d8ee2b06f3a47ed08239e4f52cec8aa8e49b6ef6)