servo is using rust_openssl and they think that only setting DEP_OPENSSL_INCLUDE fixes the lib inclusion in osx 10.11 (you can see in: https://github.com/servo/servo/blob/master/README.md#os-x) to which I sent a pull-request, but I had to set three env vars to get servo to link against brew installed openssl: https://github.com/servo/servo/pull/13225/files

Can the docs be improved or this variable be removed (in preference of the OPENSSL_* ones)