agent: Refactor ECC KEM decap operation.
* agent/pkdecrypt.c (ecc_table): Don't include shared_len. (ecc_pgp_kem_decap): Rename from ecc_pgp_kem_decrypt and only do ECC KEM decap operation. (composite_pgp_kem_decrypt): Move ECC KDF call here.
- GnuPG-bug-id: T7649
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>