* g10/keygen.c (curve_is_448): New.
(do_create_from_keygrip): Pass arg keygen_flags byref so that it can
be updated.  Set v5 flag for X448.
(gen_ecc): Ditto.
(do_create): Change keygen_flags as above.  For robustness change
checking for Ed448.
(do_generate_keypair): Change keygen_flags as above
(generate_subkeypair): Ditto.
(gen_card_key): Ditto. Support v5 keys.