Make *some* version of the Win GN build work.

build/secondary/third_party/nss/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/linux/pkg_config.gni")
 
 if (is_linux) {
   # This is a dependency on NSS with no libssl. On Linux we use a built-in SSL
   # library but the system NSS libraries. Non-Linux platforms using NSS use the
   # hermetic one in //third_party/nss.
@@ skipping 1141 matching lines @@
           "NSS_X86",
           "_X86_",
           "MP_ASSEMBLY_MULTIPLY",
           "MP_ASSEMBLY_SQUARE",
           "MP_ASSEMBLY_DIV_2DX1D",
           "MP_USE_UINT_DIGIT",
           "MP_NO_MP_WORD",
           "USE_HW_AES",
           "INTEL_GCM",
         ]
+        sources -= [
+          "nss/lib/freebl/mpi/mpi_amd64.c",
+        ]
+
       } else if (cpu_arch == "x64") {
         sources -= [
           "nss/lib/freebl/intel-aes-x86-masm.asm",
           "nss/lib/freebl/mpi/mpi_amd64.c",
           "nss/lib/freebl/mpi/mpi_x86_asm.c",
         ]
         defines += [
           "NSS_USE_64",
           "NSS_X86_OR_X64",
           "NSS_X64",
@@ skipping 33 matching lines @@
       ":nspr",
       "//third_party/sqlite",
     ]
 
     if (is_win && cpu_arch == "x86") {
       deps += [ ":nss_static_avx" ]
     }
   }
 }  # Windows/Mac/iOS.