www/obhttpd: Update to 6.6.20191023

Also, depend on standalone LibreSSL rather than security/libressl port.
Now this port can be installed even if LibreSSL is not selected in DEFAULT_VERSIONS.

PR: 241480
Submitted by: Nikola Kolev <koue@chaosophia.net>
Reported by: Leo Vandewoestijne