Make mod_ucam_webauth work with MacOS Apache

[jw35]

Apple have removed OpenSSL from MacOS, so m_u_w can no longer be built there. Presumably they have some replacement technology for supporting SSL/TLS (with mod_ssl or otherwise) and perhaps m_u_w could be adapted to work with this?

Current alternatives are to use Homebrew Apache, to move to mod_shib (but does that work on current MacOS, and if so how?), or to move to a Linux server.

RAVEN109 in master TODO list