• Remove ONLY_FOR_ARCHS restriction as chronyd(8) runs fine on PowerPC now
• Remove no-op OPTIONS_DEFAULT=IPV6, which was bogusly re-added in r416385 by pi@ after it was previously removed by amdmi3@ in r416447
• Sanitize `post-stage' target recipe (still needs more work to decouple extra docs and examples properly and add them to OPTIONS_DEFINE)

Tested on: Mac mini G4 (powerpc)