ldns: 1.7.0 -> 1.7.1

https://www.nlnetlabs.nl/news/2019/Jul/26/ldns-1.7.1-released/

* examples no longer can be configured separately,
  so build everything we want in a single go
  and sort into the appropriate outputs after.
* libtool file doesn't seem to reference openssl at all
  so nothing to patch up there as we did previously.