This means a `ClientConfig` and `ServerConfig` can be asked whether it
is in fips mode, and it answers by asking the same of all its
constituent cryptography.
It isn't possible to write a cfg expression that says when this
is used, because it would differ over the two instantiations.
Note that HMAC-SHA512 is only actually used to run test vectors posted
to the tlswg mailing list by some random in 2009.
Provide shims for limited number of places where ring 0.17 and
aws-lc-rs (ring 0.16-era) APIs have diverged. This is a
short-term fix, as they are likely to diverge more over time.
Eventually we'll have to stop sharing the code like this.
For unit-like tests, export a `test_provider` alias that resolves
to a provider module, for use in these tests.
This resolves to:
- *ring* if cfg(feature = "ring"), else
- aws-lc-rs if cfg(feature = "aws_lc_rs"), else
- is absent