Update statuses and add tests for C89 DRs

This mostly finishes the DRs for C89, though there are still a few
outliers which remain. It also corrects some of the statuses of DRs
where it's not clear if it was fully resolved by the committee or not.

As a drive-by, it also adds -fsyntax-only to the tests which are
verifying diagnostic results. This was previously missed by accident.