Support X25519 and X448.
* src/ecdh.c (ntbtls_ecdh_read_params): Add X25519 and X448. (gen_d): Likewise. (_ntbtls_ecdh_make_public, _ntbtls_ecdh_calc_secret): Likewise. (src/protocol-cli.c): Add the two curves.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>