Remove bcopy(), bzero(), bcmp()

bcopy() has a confusing argument order and is actually a move, not a
copy; they're all deprecated since POSIX.1-2001 and removed in -2008,
and we shim them out to mem*() on Linux anyway

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12996

module/zfs/hkdf.c

@@ -132,7 +132,7 @@ hkdf_sha512_expand(uint8_t *extract_key, uint8_t *info, uint_t info_len,
 		if (ret != CRYPTO_SUCCESS)
 			return (SET_ERROR(EIO));
 
-		bcopy(T, out_buf + pos,
+		memcpy(out_buf + pos, T,
 		    (i != N) ? SHA512_DIGEST_LENGTH : (out_len - pos));
 		pos += SHA512_DIGEST_LENGTH;
 	}