ssl_set1_host() is not available without openssl-1.1.0. Unbound can not do
host cert verification. DNS over TLS connects, but hosts are unverified. A
patch for log err is added with a noitce in README.md.
(see: https://www.nlnetlabs.nl/bugs-script/show_bug.cgi?id=658)

Also, squash some minor robustness and TLS usability fixes.

Signed-off-by: Eric Luehrsen <ericluehrsen@gmail.com>