ECC Fixes.

* agent/cvt-openpgp.c (get_keygrip, convert_secret_key)
(convert_transfer_key): Follow newer (>= 1.6) libgcrypt API, which
does not distinguish the detail.
(do_unprotect, convert_from_openpgp_main): Don't call
map_pk_openpgp_to_gcry, as it's the value of libgcrypt API already and
not the value defined by OpenPGP.
(convert_to_openpgp): It's "ecc".
* agent/gpg-agent.c (map_pk_openpgp_to_gcry): Remove.
* g10/call-agent.c (agent_pkdecrypt): Fix off-by-one error.
* g10/pubkey-enc.c (get_it): Fix swapping the fields error.