The dst_key_pubcompare() and dst_key_compare() didn't have a unit test,
add the unit tests which test comparing the same keys, different keys,
and, where possible, similar keys with a manually altered parameter.
dst_key_pubcompare() internally uses the *_todns() functions of the
lib/dns/openssl*_link.c modules.
dst_key_compare() internally uses the *_compare() functions of the
lib/dns/openssl*_link.c modules.
7101afa23c