Adhere to draft-ietf-dnsop-nsec-ttl with signing
Enable with --enable-rrtype-svcb-https.
* bugfix #117: Assertion failure with DNSSEC validating of
non existence of RR types at the root. Thanks ZjYwMj
+ * Set NSEC(3) ttls to the minimum of the MINIMUM field of the SOA
+ record and the TTL of the SOA itself. draft-ietf-dnsop-nsec-ttl
1.7.1 2019-07-26
* bugfix: Manage verification paths for OpenSSL >= 1.1.0
