tools: Use new API of libgcrypt for gpg-pair-tool.
* tools/gpg-pair-tool.c (create_dh_keypair): Just use gcry_random_bytes for secret. Call gcry_ecc_mul_point with G to get the public key. (compute_master_secret): Use gcry_ecc_mul_point.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>