kdf, crypto: rename unused functor parameters to [_]
Warning 67 (unused-functor-parameter). The HMAC/SHA-based functors all
take a [Digestif.S] at functor level but the hash choice is baked into
the resulting module's body; the signature of the returned module has
no reference to the parameter type. Same for Block.Core params in
cipher-block mode functors (ECB_of, CBC_of, GCM_of, CCM16_of).
Files:
- kdf/hkdf/hkdf.mli, kdf/pbkdf/pbkdf.mli: Make
- ocaml-crypto/lib/cipher_block.mli: ECB_of, CBC_of, GCM_of, CCM16_of
- ocaml-crypto/rng/{crypto_rng,hmac_drbg}.mli: Make / Hmac_drbg
- ocaml-crypto/pk/{rsa,dsa,crypto_pk}.mli: OAEP, PSS, K_gen
- ocaml-crypto/ec/crypto_ec.{ml,mli}: K_gen