Reinstall the items that were causing segfaults

Must have been running things with the wrong version of yacc :/
Always wipe out the yacc hardlink
Revert "Skip over failing testcases (needs the latest byacc snapshot)"

This reverts commit ef91650dbd9fb94a54f67329e906881175c77648.

Then, refine the check to skip over the failing testcases
Partially revert 8fe9adffdf4b0e01870520711936e91f4be67919 to restore -D output