Hello,

the attached patch adds libressl. As you can see, it is quite a bit simpler
than the openssl package, which already inspires confidence. I think we
should add the package; the next question would be whether we should switch
all inputs from openssl to libressl. I tried it for fetchmail, and it works
just the same.

I also wonder whether we should not unite gnutls.scm and openssl.scm into
one tls.scm.

What do you think?

Andreas