Log Message:
Upgrade unbound to version 1.6.7.

Pkgsrc changes:
 * None.

Upstream changes:

Features:
* Set trust-anchor-signaling default to yes
* Fix #1440: [dnscrypt] client nonce cache.
* Fix #1435: Please allow UDP to be disabled separately upstream and
  downstream.

Bug fixes:
* Fix that looping modules always stop the query, and don't pass
  control.
* Fix unbound-host to report error for DNSSEC state of failed lookups.
* Spelling fixes, from Josh Soref.
* Fix #1400: allowing use of global cache on ECS-forwarding unless
  always-forward.
* use a cachedb answer even if it's "expired" when serve-expired is yes
  (patch from Jinmei Tatuya).
* trigger refetching of the answer in that case (this will bypass
  cachedb lookup)
* allow storing a 0-TTL answer from cachedb in the in-memory message
  cache when serve-expired is yes
* Fix DNSCACHE_STORE_ZEROTTL to be bigger than 0xffff.
* Log name of looping module
* Fix #1450: Generate again patch contrib/aaaa-filter-iterator.patch
   (by Danilo G. Baio).
* Fix param unused warning for windows exportsymbol compile.
* Use RCODE from A query on DNS64 synthesized answer.
* Fix trust-anchor-signaling works in libunbound.
* Fix spelling in unbound-control man page.