openssh: refer to OpenSSL not SSLeay

This change was made upstream between 7.9p1 and 8.0p1. We've made local
changes in the same places for handling the version_addendum; apply the
SSLeay_version to OpenSSL_version change in advance of importing 8.0p1.

Obtained from: OpenSSH-portable a65784c9f9c5
Sponsored by: The FreeBSD Foundation