This finishes the last step of removing sodium.rs from the rosenpass crate
itself and also removes the NOTHING and NONCE0 constants.
Hashing functions now use destination parameters;
rosenpass_constant_time::xor now does too.
When fuzzing we are interested in what happens inside the target function
not necessarily what it returns. Functions returning errors with bogus
input in generally desired behaviour.
These targets can be used with rust nightly and cargo-fuzz to fuzz
several bits of Rosenpass's API. Fuzzing is an automated way of
exploring code paths that may not be hit in unit tests or normal
operation. For example the `handle_msg` target exposed the DoS condition
fixed in 0.2.1.
The other targets focus on the FFI with libsodium and liboqs.
Co-authored-by: Karolin Varner <karo@cupdev.net>
