Enable the gathering of crypto stats.

Enabling this option reduces the performance of the crypto API. It
should only be enabled when there is actually a use case for it.

This collects data sizes, numbers of requests, and numbers
of errors processed by:
- AEAD ciphers (encrypt, decrypt)
- asymmetric key ciphers (encrypt, decrypt, verify, sign)
- symmetric key ciphers (encrypt, decrypt)
- compression algorithms (compress, decompress)
- hash algorithms (hash)
- key-agreement protocol primitives (setsecret, generate
public key, compute shared secret)
- RNG (generate, seed)