tests: Adjust positive tests to verify both parse directions.

tests: Adjust positive tests to verify both parse directions.

We don't actually have any canned tests of the "declare" or "type"
commands to produce C syntax from pseudo-English.  While the randomized
crossparse test does provide some coverage of this, failures here
are difficult to understand compared to more simple, standalone test
cases.

So to start, let's just expand the existing "positive" tests to check
in both directions.