tc_sha256_final() function

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: s == NULL, s->iv == NULL, digest == NULL

Assumes: s has been initialized by tc_sha256_init digest points to at least TC_SHA256_DIGEST_SIZE bytes @warning The state buffer 'leftover' is left in memory after processing If your application intends to have sensitive data in this buffer, remind to erase it after the data has been processed