revert: #33 and #36 seem to PnR dependent on icebreaker, revert until root cause found

[schnommus]

• The pitch shift and vco examples seem to be broken sometimes after PnR with the clocking rewrite from #33 and #35
• Let's revert them so HEAD is stable
• In the background we need a system-level integration test, maybe that could help catch these kind of things