Change the default value of VerifyHostKeyDNS to "yes" if compiled with
LDNS.  With that setting, OpenSSH will silently accept host keys that
match verified SSHFP records.  If an SSHFP record exists but could not
be verified, OpenSSH will print a message and prompt the user as usual.

Approved by:	re (blanket)
Missed in r255386: libssh is more than just the .so file itself.

Approved by:	re (blanket)