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

test/win/gyptest-cl-enable-enhanced-instruction-set.py

Index: test/win/gyptest-cl-enable-enhanced-instruction-set.py
===================================================================
--- test/win/gyptest-cl-enable-enhanced-instruction-set.py	(revision 2027)
+++ test/win/gyptest-cl-enable-enhanced-instruction-set.py	(working copy)
@@ -28,7 +28,7 @@
 
   # /arch:AVX introduced in VS2010, but MSBuild support lagged until 2012.
   if os.path.exists(test.built_file_path('avx_extensions')):
-    test.run_built_executable('no_extensions', chdir=CHDIR,
+    test.run_built_executable('avx_extensions', chdir=CHDIR,
                               stdout='/arch:AVX\n')
 
   # /arch:IA32 introduced in VS2012.
@@ -36,4 +36,9 @@
     test.run_built_executable('no_extensions', chdir=CHDIR,
                               stdout='/arch:IA32\n')
 
+  # /arch:AVX2 introduced in VS2013r2.
+  if os.path.exists(test.built_file_path('avx2_extensions')):
+    test.run_built_executable('avx2_extensions', chdir=CHDIR,
+                              stdout='/arch:AVX2\n')
+
   test.pass_test()