cipher: Add sntrup761 to KEM API.
* cipher/kem.c (sntrup761_random): New glue code. ( _gcry_kem_keypair, _gcry_kem_encap, _gcry_kem_decap): Call sntrup761 functions. * cipher/sntrup761.h: Add glue code to libgcrypt. * src/visibility.h: Update for KEM functions. * tests/t-kem.c: Fix for the final KEM API.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>