macxconf: remove openssl

OpenSSL isn't actually a dependency of QBT, as discussed [here](https://github.com/qbittorrent/qBittorrent/issues/2282#issuecomment-66970670), but rather of ` libtorrent-rasterbar `. But this file containing directions to OpenSSL is resulting in a consistent situation where QBT ends up dragging in the defunct OS X default OpenSSL with every build and run. We can get rid of it safely, and solve the issue.

Long-term, I think Sledge wants to move to autotools everywhere, so that'd presumably eliminate this file altogether.