Remove crypto/curve25519.h in favor of BoringSSL's.

crypto/curve25519.cc

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "crypto/curve25519.h"
-
-#include <stdint.h>
-
-#include "third_party/boringssl/src/include/openssl/curve25519.h"
-
-namespace crypto {
-
-namespace curve25519 {
-
-bool ScalarMult(const uint8_t* private_key,
-                const uint8_t* peer_public_key,
-                uint8_t* shared_key) {
-  return !!X25519(shared_key, private_key, peer_public_key);
-}
-
-void ScalarBaseMult(const uint8_t* private_key, uint8_t* public_key) {
-  X25519_public_from_private(public_key, private_key);
-}
-
-}  // namespace curve25519
-
-}  // namespace crypto