* cipher/hash-common.c (_gcry_hash_selftest_check_one): Adjust
for SHAKE algorithms now returning non-zero for digest length.
* cipher/keccak.c (KECCAK_CONTEXT_S): Add 'shake_in_extract_mode'
and 'shake_in_read_mode' flags.
(keccak_init): Initialize new context fields; set output length
for SHAKE algorithms.
(keccak_extract): Rename to ...
(do_keccak_extract): this and add return value.
(keccak_extract): New with 'shake_in_???_mode' checks & setup.
(keccak_shake_read): New.
(_gcry_sha3_hash_buffers): Adjust for 'spec->mdlen' not being
zero for SHAKE algorithms, instead check 'suffix' for type.
(_gcry_digest_spec_shake128): Set mdlen to 32 bytes; Set read
function.
(_gcry_digest_spec_shake256): Set mdlen to 64 bytes; Set read
function.
* cipher/md.c (md_extract): Pass return value from algo extract
function.
(_gcry_md_hash_buffers_extract): Adjust for 'spec->mdlen' not
being zero for SHAKE algorithms.
* src/cipher-proto.h (gcry_md_extract_t): Change return type
from 'void' to 'gpg_err_code_t'.
* tests/basic.c (check_one_md, check_one_md_multi): Adjust
for 'gcry_md_get_algo_dlen()' not being zero for SHAKE
algorithms.
(check_digests): Add md_read interface test-vectors for SHAKE128
and SHAKE256.