* cipher/kdf.c (struct argon2_thread_data): Change layout.
(argon2_iterator): Use struct gcry_kdf_pt_head.
(argon2_compute_segment): Rename from argon2_compute_row.
(argon2_open): Handle N_THREAD maximum.
(_gcry_kdf_iterator): Use struct gcry_kdf_pt_head.
(_gcry_kdf_compute_segment): Rename from _gcry_kdf_compute_row.
* src/gcrypt-int.h: Update declarations.
* src/gcrypt.h.in (struct gcry_kdf_pt_head): Expose the data type.
* src/libgcrypt.def, src/libgcrypt.vers: Update.
* src/visibility.c, src/visibility.h: Update.
* tests/t-kdf.c (start_thread, my_kdf_derive): Follow the change.