Delete bundled copy of NSS and replace with README.

nss/lib/freebl/mpi/mpi_amd64.c

-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef MPI_AMD64
-#error This file only works on AMD64 platforms.
-#endif
-
-#include <mpi-priv.h>
-
-/*
- * MPI glue
- *
- */
-
-/* Presently, this is only used by the Montgomery arithmetic code. */
-/* c += a * b */
-void MPI_ASM_DECL s_mpv_mul_d_add_prop(const mp_digit *a, mp_size a_len,
-                                       mp_digit b, mp_digit *c)
-{
-  mp_digit w;
-  mp_digit d;
-
-  d = s_mpv_mul_add_vec64(c, a, a_len, b);
-  c += a_len;
-  while (d) {
-    w = c[0] + d;
-    d = (w < c[0] || w < d);
-    *c++ = w;
-  }
-}
-