[Swan-dev] runtime detection of NSS capabilities: SSL_GetImplementedCiphers()

[Paul Wouters]

The function to check for cryptographic algorithms in NSS appararently
is the function SSL_GetImplementedCiphers()

Eg, we need to use that so see if we have CHACHA20/POLY1305 support in
the future. Probably we also need it to test for various CCM algos
needed to support IoT devices that we know aren't all in NSS yet.

Paul