ensureSocksPort

If TorOption.SocksPort or TorOption.__SocksPort are not defined, add TorOption.__SocksPort (with its default of 9050) so that it can be checked for availability on the host and set to auto, if needed.

This can be overridden by defining TorOption.SocksPort or TorOption.__SocksPort, and then assigning a value of false for BuilderScopePort.Socks.reassignable.

e.g.

TorOption.__SocksPort.configure {
    // argument is already `9050`, tor's default

    reassignable(false)
}