agent: Support ECC KEM by PKDECRYPT --kem.
* common/kem.c (gnupg_ecc_kem_kdf): Support traditional KDF of RFC 6637. * common/util.h (gnupg_ecc_kem_kdf): Add FIXED_INFO argument. * g10/pkglue.c (do_encrypt_kem): Follow the change. * agent/pkdecrypt.c (ecc_pgp_kem_decap): Return ECC parameters. (composite_pgp_kem_decrypt): Follow the changes. (ecc_kem_decrypt): New. (agent_kem_decrypt): Support ECC KEM.
- GnuPG-bug-id: T7649
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>