This is enough to get a chutney network to bootstrap, though a bunch
of work remains.

7 unit tests are failing at this point, but they're all TLS-related.

We used to link both libraries at once, but now that I'm working on
TLS, there's nothing left to keep OpenSSL around for when NSS is
enabled.

Note that this patch causes a couple of places that still assumed
OpenSSL to be disabled when NSS is enabled
   - tor-gencert
   - pbkdf2

Also, add a stubbed-out nss version of the modules.  The tests won't
pass with NSS yet since the NSS modules don't do anything.

This is a good patch to read with --color-moved.