win: 'EnableEnhancedInstructionSet': '5' now enables /arch:AVX2.

test/win/compiler-flags/enable-enhanced-instruction-set.cc

 // Copyright (c) 2014 Google Inc. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdio.h>
 
 static const char* GetArchOption() {
 #if _M_IX86_FP == 0
   return "IA32";
 #elif _M_IX86_FP == 1
   return "SSE";
 #elif _M_IX86_FP == 2
 #  if !defined(__AVX__)

[bradn, 2015/01/23 18:31:08]

FWIW, might be clearer if these were stated in the positive and in reverse, but
either way.

[Nico, 2015/01/23 18:31:44]

That's a great suggestion, done.

   return "SSE2";
+#  elif !defined(__AVX2__)
+  return "AVX";
 #  else
-  return "AVX";
+  return "AVX2";
 #  endif
 #else
   return "UNSUPPORTED OPTION";
 #endif
 }
 
 int main() {
   printf("/arch:%s\n", GetArchOption());
   return 0;
 }